Tranning Report Civil Enggineering

Construction of an Interchange at 0-00 km at Yamuna Expressway Project A Practical Training Report On Yamuna expressway project, Noida From 15.05.2010 to 14-06-2010 Submitted in Partial Fulfillment of the Requirements for the Degree of BACHELOR OF TECHNOLOGY in Civil Engineering

Submitted to:

Submitted by:

Vimal Gahlot

Abhishek Mathur

Reader & Head

Civil- Final year

Department of Civil Engineering COLLEGE OF ENGINEERING & TECHNOLOGY BIKANER Bikaner 334001, INDIA AUGUST, 2010

Abstract This report is a summer internship report submitted in partial fulfillment

of

the

requirements

for

the

degree

of

Bachelor

of

Technology in Civil Engineering as per norms of Rajasthan Technical University Kota. The author visited the site for construction of trump interchange structure, at Yamuna expressway, Noida in his training period and attained technical knowledge during the course, after which he was able to compile this report. The report consists of brief study and description of materials, equipments and procedures used at site for construction of an interchange. Author put his best to elaborate the actual site conditions, and problem faced at site and the tactics used to deal with them. The main objective of this report is to present a systematic text on the execution of construction of an interchange based on the Indian Standard codes. The report also covers the fundamental aspects of practical requirement such as safety, feasibility and economy at site. In this report the objective was to introduce, wherever necessary, material which embodies the most recent methodologies. Chapter 1 discusses introduction to organization profile, management structure, products, plants, capacity, turnover, market share, problem definition (objectives, deliverables etc), and the main conclusions. Chapter 2 deals with materials and equipments used at site, literature review. Chapter 3 contains description of the process plant/site where practical training was undertaken including block diagrams for showing process scheme, major operations and process equipments, stream compositions, site conditions governing the process control. Chapter 4 discusses summary of the project with main findings and conclusions, the method of adoption of the proposed solution by the organization

i

and expected benefits (technical and financial) Chapter 5 presents the results obtained after the tests performed on site proceeding with their conclusion. In spite of every care taken, it is possible that some errors might have been left unnoticed. The author sincerely welcomes the constructive criticism for improving the report.

ii

iii

Certificate

It is certified that the work contained in this training report titled “Construction of interchange at 0-00 km at Yamuna Expressway project, Noida" is the original work done by Abhishek Mathur (07ECTCE003) and has not been submitted anywhere.

(Vimal Gahlot) Date:

Reader & Head

Place:

Department of Civil Engineering College of Engineering & Technology Bikaner 334001

iv

Acknowledgment

I take immense pleasure in thanking Prof. R.C Gaur, Principal, College of Engineering & Technology, Bikaner and Mr.Vimal Gahlot, (Reader, civil department) for having permitted me to carry out this training. I wish to express my deep sense of gratitude to my teachers, Mr. Surender beniwal, Mrs Pratibha Choudhary, Mrs. Karanjeet kaur, civil department, for their able encouragement and useful suggestions, which helped me in completing the training work, in time.

Needless to mention that Mr.Ramesh Kamboj,(Vice President projects V.N.C) and Mr.K Mohan (project manager V.N.C), who had been a source of inspiration and for his timely guidance in the conduct of my training. I would also like to thank Mr.Rajesh pustry, Mr.Sudarhan Murty, Mr. Garurav Maroo and Mr.Dinesh Pawar of for all their valuable assistance during training.

Words are inadequate in offering my thanks to the Project team of Vijay Nirman Construction company for their guidance and cooperation in carrying out the training work.

Finally, yet importantly, I would like to express my heartfelt thanks to my beloved parents for their blessings, my friends/classmates for their help and wishes for the successful completion of this training.

v

Table of Contents Abstract

i

Certificate from company

iii

Certificate

iv

Acknowledgement

v

Chapter 1: Introduction

1-9

1.1

Company’s Profile

1

1.2

Project Profile

3

1.3

Interchange

6

Chapter 2: Material & Equipment 2.1

2.2

10-33

Materials

2.1.1 Cement

10

2.1.2 Coarse aggregate

11

2.1.3 Fine aggregate

11

2.1.4 Reinforcement bar

12

2.1.5 Water

14

2.1.6 Admixture

17

2.1.7 RMC

19

Equipments

20

2.2.1 Batch Mix Plant

20

2.2.2 Transit mixer

23

2.2.3 Post tensioning

23

2.2.3.1 Duct

23

2.2.3.2 Bearing plate

24

2.2.3.3 Wedges

25

2.2.3.4 Jack

27

2.2.3.5 Meter Gauge

28

2.2.4 Grouting

28 vi

2.2.4.1 Mixer

29

2.2.4.2 Storage Hopper & screens

29

2.2.4.3 Grout pumps

30

2.2.4.4 Pressure gauge

31

2.2.4.5 Hoses

31

2.2.5 Auto Level Chapter 3: Structural Components

31 34-79

3.1 Sub Structure 3.1.1 Foundation

34

3.1.2 Pile cap

36

3.1.3 Piers

38

3.2 Super Structure 3.2.1 Piers cap

39

3.2.2 Bearing

46

3.2.3 Precast Girder

52

3.2.4 Diaphragm wall

75

Chapter 4: Results & Discussions

80-88

4.1Test for Aggregate

80

4.2Test for Reinforcement

83

4.3Test for Concrete

85

Chapter 5: Construction management

89-95

5.1 Basic concept

89

5.2 Choice of technology & method

90

5.3 Work task

91

5.4 Relationship among activities

91

5.5 Estimating activity duration

92

5.6 Resource requirement

93

5.7 Reporting

93

5.8 Safety

93 vii

Conclusion Appendix

96 97-109

Appendix I

97

Appendix II

100

Appendix III

105

Appendix IV

108

Reference

110

Suggestions

viii

Chapte r INTRODUCTION

1

1.1 Company’s Profile VIJAY NIRMAN COMPANY was established in the year 1982 by Dr. S. Vijaya Kumar. The company started its operation from Visakhapatnam, port city of Andhra Pradesh, India with construction of Industrial structures and Pile foundations. Over the years, Vijay Nirman Company has expanded into the fields of marine work (Berths/Jetties), power projects, road and bridges, electrical sub stations, residential and commercial buildings, and water works. Vijay Nirman has also executed silos & chimneys involving slip form technology. Vijay Nirman has completed more than 350 projects to date, and maintains an arbitration–free record, with all over India and an Annual turnover of ` 400 cores, projected for the year 2010-2011 Corporate social responsibility environment philosophy they believe is that as long as we are in harmony with nature, it will provide us with everything in abundance, at the appropriate time 1.1.1 Turnover

7000 6000 5000 4000 3000 2000 1000 0

`6450

Rs.inMilions `4500 `2700 `610

`940

`811

`870

2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11

1

1.1.2 Major Projects Completed by Vijay Nirman Industrial /Defense Projects

Roads & Bridges

Power Plants

Marine Works

Buildings Works

Material Handling Projects

Workshops building at NYC site A at Naval Dockyard, Visakhapatnam, involving 6000MT of structural steel fabrication & erection; Sulphur Recovery Unit for HPCL, Visakhapatnam; Aluminum alloy wheel plant at Duvvada, Visakhapatnam; Wet Process unit for Transworld Garnet India, Visakhapatnam. Western Transport Corridor Tumkur-Haveri NH4 project; Rail Bridge across Lakshamanteertha river,Mysore; R.B. across river Pennaiyar 600 mt, Melpattambakkam; Road over bridge near Pakur Station, Jharkand; Main Carriage Way of elevated highway of Hosour road; Underpasses & ROBs construction/strengthening of existing two lane TindivanamUlundurpet section of NH45. 208MW combined cycle power plant at Kakinada, involving 5 cell RCC cooling tower; 1x300MW Captive Power Plant for ARYAN Coal Benefications Pvt Ltd; captive power plant at Bhadrak; 30 MW Diesel Power Plant near Visakhapatnam.

Construction of Jetty for ONGC in Fisheries’ harbor, Visakhapatnam; Construction of sea Water Intake System and approach jetty, Srikakulam; Construction of Pipe bridge of total length 2200 Kakinada; Pile foundation for Matsya Dock at Naval Dockyard, Visakhapatnam; Upgradation and renovation of Fishing Harbor at Visakhapatnam. Construction of new building for Bharat Electricals, Bangalore; Expansion of Chinnaswamy Cricket Stadium, Bangalore; HIGH IQ luxury apartment, Bangalore; Construction of Independent Villas, Housar road, Bangalore; Chaulukya Holidays Resort, Bangalore; Sea Valley Resorts, Construction of Wagon Tippler & other facilities for handling iron ore and coal a Ganagavaram Port; Expansion of Alumina handling Facilities at Nalco’s Port facility, Visakhapatnam.

2

1.2 Project Profile

‘Yamuna Expressway Project’ at a glance The Government of Uttar Pradesh has been working proactively to improve the connectivity of the National Capital Region to improve tourist attraction of Taj Mahal at Agra through the new 6 lanes (extendable to 8 lanes) Access Controlled Expressway with brand name of Yamuna Expressway (erstwhile Taj Expressway). Almost everyone who comes to India makes it a point to make a trip to the Taj Mahal, Agra. Presently Agra is about 210 km from Delhi by road. It takes normally nine to ten traveling hours on a return trip between Delhi and Agra which leaves very less time in Agra to see the Taj and other places of historical importance. The concept of the Yamuna Expressway (erstwhile Taj Expressway proposes a 160 km Expressway between Greater Noida and Agra thus reducing the travel time to 100 minutes only. For implementing the Yamuna Expressway Project and allied development in the region, Government of UP constituted Taj Expressway Industrial Development Authority (TEA) vide its Notification No.697/77-4-20013(N)/2001

dated

Development

Act,

24th 1976

April, (U.P.

2001, Act

under No.6

U.P. of

Industrial

1976).

The

Area main

responsibilities of TEA, inter alia, included: 

Execution of Yamuna Expressway.



Acquisition of land for construction of Expressway.



Preparation of Zonal/Master plan for planned development along the Expressway. 3



Development of drainage, feeder roads, electrification and other facilities in the area.

Approx. 334 villages of District Gautam Buddh Nagar, Bulandshahar, Aligarh, Mahamaya Nagar (Hathras), Mathura and Agra are Notified under Yamuna Expressway Industrial Development Authority vide various Notifications of Government of UP. 1.2.1 Project Map

Fig. 1.1: Map of Yamuna Expressway

4

Table 1: Quick Facts about Yamuna Expressway Length

165.537Km

Right of Way

100m

Number of lane

6 lane, extendable to 8 Lanes

Type of Pavement

Rigid (Concrete)

Cost

`1400 millions

Structures Interchange

7

Main Toll Plaza

3

Toll Plaza on interchange loop 7 Underpass

35

Rail Over Bridge

1

Major Bridge

1

Minor Bridge

42

Cart Track Crossing

68

Culverts

204

5

1.3 Interchange

Fig. 1.2: A typical interchange In the field of road transport, an interchange is a road junction that typically uses grade separation, and one or more ramps, to permit traffic on at least one highway to pass through the junction without directly crossing any other traffic stream. It differs from a standard intersection, at which roads cross at grade. Interchanges are almost always used when at least one of the roads is a limited-access divided highway (expressway or freeway), though they may occasionally be used at junctions between two surface streets. At rotary intersection weaving is an undesirable situation in which traffic veering right and traffic veering left must cross paths within a limited distance, to merge with traffic on the through lane. In the worst circumstances, a large portion of through traffic must change lanes to stay on the same roadway. Weaving creates both safety and capacity 6

problems. Some interchanges use collector/distributor roads to deal with weaving-while doing so does not eliminate the problem entirely. Collector/distributor

roads

separate

the

weaving

traffic

from

the

highway's main lanes or carriageway, thus improving traffic flow. Some areas that had such bad junctions have gone through the expensive process of ‘unweaving the weave’ to improve traffic flow. Another way to avoid weaving is to have braided ramps, in which an on-ramp passes over or under an off-ramp using an overpass structure such as interchange.

7

1.3.1 Types of Interchange 1.3.1.1 Four-way interchanges A cloverleaf interchange is typically a two-level, Cloverleaf

four-way interchange whereby all left turns are handled by loop ramps (right turns if traveling on the left). To go left, vehicles first cross over or under the targeted route, then bear right onto a sharply curved ramp that loops roughly 270 degrees, merging onto the interchanging road from the right, and crossing the route just departed.

Stack

Clover stack

Turbine

A stack interchange is where left turns are handled by semi-directional flyover/under ramps. Vehicles first turn slightly right (on a right-turn off-ramp) to exit, and then complete the turn via a ramp which crosses both highways, eventually merging with the right-turn on-ramp traffic from the opposite quadrant of the interchange. A stack interchange, then, has two pairs of left-turning ramps, of which can be stacked in various configurations above or below the two interchanging highways. Partial cloverleaf interchange (parclo) is design modified for freeway traffic emerged, eventually leading to the clover stack interchange. Its ramps are longer to allow for higher ramp speeds, and loop ramp radii are made larger as well. For countries using right hand-drive, the large loop ramps eliminate the need for a fourth, and sometimes a third level in a typical stack interchange, as only two directions of travel use flyover/under ramps. Another alternative to the four-level stack interchange is the turbine interchange (also known as a whirlpool). The turbine/whirlpool interchange requires fewer levels (usually two or three) while retaining semi-directional ramps throughout, and has its left-turning ramps sweep around the center of the interchange in a spiral pattern in right-hand driving.

8

(a) Windmill

(b) Diverging windmill

(c) Full diamond

Fig. 1.3: Various other types of interchanges 1.3.1.2 Three-way interchanges Trump Trumpet interchanges have been used where one highway terminates at another highway. These involves at least one loop ramp connecting traffic either entering or leaving the terminating expressway with the far lanes of the continuous highway.

Directional

T – Bone

Directional T interchange uses flyover/under ramps in all directions at a three-way interchange. A semi-directional T does the same, but some of the splits and merges are switched to avoid ramps to and from the passing lane. Directional T interchanges are very efficient, but are expensive to build compared to other three-way interchanges. They also require three levels, which can be an eyesore for local residents.

¾-volley 9

Half-Clove

10

Chapt er

2

MATERIAL & EQUIPMENT

2.1Materials 2.1.1Cement Portland cement is composed of calcium silicates, aluminates and aluminoferrite. It is obtained by blending predetermined proportions limestone clay and other minerals in small quantities which is pulverized and heated at high temperature – around 1500 deg centigrade to produce ‘clinker’. The clinker is then ground with small quantities of gypsum to produce a fine powder called Ordinary Portland Cement (OPC). When mixed with water, sand and stone, it combines slowly with the water to form a hard mass called concrete. Cement is a hygroscopic material meaning that it absorbs moisture. In presence of moisture it undergoes chemical reaction termed as hydration. Therefore cement remains in good condition as long as it does not come in contact with moisture. If cement is more than three months old then it should be tested for its strength before being taken into use. The Bureau of Indian Standards (BIS) has classified OPC in three different grades The classification is mainly based on the compressive strength of 2

cement-sand mortar cubes of face area 50 cm composed of 1 part of cement to 3 parts of standard sand by weight with a water-cement ratio arrived at by a specified procedure. The grades are

10

1. 33 grade 2. 43 grade 3. 53 grade

The grade number indicates the minimum compressive strength of cement sand mortar in N/mm2 at 28 days, as tested by above mentioned procedure. Nowadays good quality fly ash is available from Thermal Power Plants, which are processed and used in manufacturing of PPC. 2.1.2 Coarse aggregate Coarse aggregate for the works should be river gravel or crushed stone. It should be hard, strong, dense, durable, clean, and free from clay or loamy admixtures or quarry refuse or vegetable matter. The pieces of aggregates should be cubical, or rounded shaped and should have granular or crystalline or smooth (but not glossy) non-powdery surfaces. Aggregates should be properly screened and if necessary washed clean before use. Coarse aggregates containing flat, elongated or flaky pieces or mica should be rejected. The grading of coarse aggregates should be as per specifications of IS: 383-1970. After 24-hrs of immersion in water, a previously dried sample of the coarse aggregate should not gain in weight more than 5%.Aggregates should be stored in such a way as to prevent segregation of sizes and avoid contamination with fines. 2.1.3 Fine aggregate Aggregate which is passed through 4.75 mm IS Sieve is termed as fine aggregate. Fine aggregate is added to concrete to assist workability and to bring uniformity in mixture. Usually, the natural river sand is used as

11

fine aggregate. Important thing to be considered is that fine aggregates should be free from coagulated lumps. Grading of natural sand or crushed stone i.e. fine aggregates shall be such that not more than 5 percent shall exceed 5 mm in size, not more than 10% shall IS sieve No. 150 mm not less than 45% or more than 85% shall pass IS sieve No. 1.18 mm and not less than 25% or more than 60% shall pass IS sieve No. 600 micron. Table 2.1: Limits Of Fineness Moduli in aggregate Maximum size of aggregate

Fineness modulus Max.

Min.

2.0

3.5

20 mm

6.0

6.9

40 mm

6.9

7.5

75 mm

7.5

8.0

150mm

8.0

8.5

20 mm

4.7

5.1

25mm

5.0

5.5

32 mm

5.2

5.7

40 mm

5.4

5.9

75 mm

5.8

6.3

150 mm

6.5

7.0

Fine aggregate Coarse aggregate

Mixed aggregate

2.1.4 Reinforcement Bras Steel reinforcements are used, generally, in the form of bars of circular cross section in concrete structure. They are like a skeleton in concrete body. Plain concrete without steel or any other reinforcement is strong in 12

compression but weak in tension. Steel is one of the best forms of reinforcements, to take care of those stresses and to strengthen concrete to bear all kinds of loads. Mild steel bars conforming to IS: 432 (Part I) and Cold-worked steel high strength deformed bars conforming to IS:1786 (grade Fe 415 and grade Fe 500, where 415 and 500 indicate yield stresses 415 N/mm2 and 500 N/mm2 respectively) are commonly used. Grade Fe 415 is being used most commonly nowadays. This has limited the use of plain mild steel bars because of higher yield stress and bond strength resulting in saving of steel quantity. Some companies have brought thermo mechanically treated (TMT) and corrosion resistant steel (CRS) bars with added features. Bars range in diameter from 6 to 50 mm. Cold-worked steel high strength deformed

bars

start

from

8

mm

diameter.

For

general

house

constructions, bars of diameter 6 to 20 mm are used. Transverse reinforcements are very important. They not only take care of structural requirements but also help main reinforcements to remain in desired position. They play a very significant role while abrupt changes or reversal of stresses like earthquake .They should be closely spaced as per the drawing and properly tied to the main/longitudinal reinforcement. Steel has an expansion coefficient nearly equal to that of modern concrete. If this were not so, it would cause problems through additional longitudinal and perpendicular stresses at temperatures different than the temperature of the setting. Although rebar has ribs that bind it mechanically to the concrete, it can still be pulled out of the concrete under high stresses, an occurrence that often precedes a larger-scale collapse of the structure. To prevent such a failure, rebar is either deeply 13

embedded into adjacent structural members (60-80 times the diameter), or bent and hooked at the ends to lock it around the concrete and other rebar. This first approach increases the friction locking the bar into place; while the second makes use of the high compressive strength of concrete. Common rebar is made of unfinished tempered steel, making it susceptible to rusting. 2.1.5 Water Water is one of the most important elements in construction but people still ignore quality aspect of this element. The water is required for preparation of mortar, mixing of cement concrete and for curing work etc during construction work. The quality and quantity of water has much effect on the strength of mortar and cement concrete in construction work. It has been observed that certain common impurities in water affect the quality of mortar or concrete. Many times in spite of using best material i.e. cement, coarse sand, coarse aggregate etc. in cement concrete,

required

results

are

not

achieved.

Most

of

Engineers/Contractors think that there is something wrong in cement, but they do not consider quality of water being used. Some bad effects of water containing impurities are following: 1. Presence of salt in water such as Calcium Chloride, Iron Salts, inorganic salts and sodium etc. are so dangerous that they reduce initial strength of concrete and in some cases no strength can be achieved. There is rusting problem in steel provided in RCC. 2. Presence of acid, alkali, industrial waste, sanitary sewage and water with sugar also reduce the strength of concrete. 3. Presence of silt or suspended particle in water has adverse effect on strength of concrete.

14

4. Presence of oil such as linseed oil, vegetable oil or mineral oil in water above 2 % reduces the strength of concrete up to 25 %. 5. Presence of algae/vegetable growth in water used for mixing in cement concrete reduce of the strength of concrete considerably and also reduce the bond between cement paste and aggregate. It has been observed at various places that cement concrete start falling down in pieces after rusting mild steel from RCC slab, which is due to use of bad quality/salty water in RCC slab. All this is due to negligence or ignorance which creates great problems and also bears a heavy loss. It is advisable that the water must be tested before using in construction work. Limits of Solids Table 2.2: Limits of Solids Organic

200 mg/L

Inorganic

1000 mg/L

Sulphate:

400 mg/L

Chloride

500 mg/L for RCC work and 2000 mg/L for concrete not containing steel.

Suspended

2000 mg/L

matter

15

Main disadvantages of mixing too much water in mortar and concrete 

The water occupies space in sand and it evaporates to create voids. Moreover the water voids will be more and this will reduce the density, strength and durability of mortar or concrete.



When more water is used in concrete excess water brings a mixture of excess cement paste with water floating on the surface. This material forms a thin layer of chalky material on the surface which reduces proper bonding with second layer of cement concrete in case of water tank and dams etc. This will affect the strength of concrete.



When more water is used, the cement slurry starts coming out from cement concrete mix. The excess slurry formed by water and cement comes out through shuttering joints. This makes concrete of less cement and reduces the strength of concrete.



When more water is used, proper compaction is not achieved and there is bleeding, large voids and more shrinkage, less durability and less strength.



When more water is mixed in cement concrete, the problem of segregation of material is faced at the time of laying the mix. As a result Coarse Aggregate and cement paste separate from each other.

Hence strict control should be kept on water cement ratio for preparing the mortar or concrete for qualitative finish/ strength.

16

2.1.6 Admixtures Water Reducing Admixtures The water reducer admixture improves workability of concrete/mortar for the same water cement ratio. The determination of workability is an important factor in testing concrete admixture. Rapid loss of workability occurs during first few minutes after mixing concrete and gradual loss of workability takes place over a period from 15 to 60 minutes after mixing. Thus relative advantages of water reducing admixture decrease with time after mixing. These admixtures increase setting time by about 2 to 6 hrs during which concrete can be vibrated. This is particularly important in hot weather conditions or where the nature of construction demands a time gap between the placements of successive layers of concrete. Advantages 

It can reduce 10% of water consumption.



It can improve mixture of cement concrete for workability.



Compression strength improves by more than 15 %.



It can reduce initial stage of cement heat hydration by large margin.



It has no function of corrosion reinforcing bars.



It increases workability, density and strength without increasing the quantity of cement.

17

Table 2.3 Type of admixture Type of admixture

Performance

Water reducing/plasticizing

Water reduction at equal consistence Water Reduction ≥ 5%

High-range water

Water reduction at equal consistence

reducing/superplasticizing

Increase in consistence at equal w/c ratio Water Reduction ≥ 12% Slump increase ≥ 120 mm

Water retaining

Reduction in bleeding Shrinkage Reduction ≥ 50%

Water resisting

Reduction in capillary absorption Reduction ≥ 50% by mass

Air entraining

Air void characteristics in hardened concrete Spacing factor ≤ 0.200 µm

Set accelerating

Reduction in initial setting time Initial setting time

Reduction ≥ 40%

at 5°C Hardening accelerating

Compressive

strength

at

1

day

Increase ≥ 20% at 20°C Compressive

strength

Increase ≥ 30% at 5°C

18

at

2

days

Set retarding

Increase in initial and final setting time Initial setting time increase ≥ 90 min. Final increase ≤ 360 min

Set retarding/water

Water reduction at equal consistence

reducing/plasticizing

Increase in initial and final setting time Water Reduction ≥ 5% Initial setting time increase ≥90min. Final setting time increase ≤ 360 min.

Set retarding/high-range

Water reduction at equal consistence

water reducing/superplasticizing

Increase in consistence at equal w/c ratio Increase in initial and final setting time at equal consistence Water Reduction ≥ 12% Slump increase ≥ 120 mm Initial setting time increase ≥ 90 min. Final setting time increase ≤ 360 min.

Set accelerating/water

Water reduction at equal

reducing/plasticizing

Consistence Reduction in initial setting time Reduction ≥ 5% Reduction ≥ 30 min. at 20°C and ≥ 40% at 50C

2.1.7 Ready Mix Concrete (RMC) Ready-mix concrete is a type of concrete that is manufactured in a factory or batching plant, according to a set recipe, and then delivered to a work site, by truck mounted transit mixers. This results in a precise mixture, allowing specialty concrete mixtures to be developed and 19

implemented on construction sites. Concrete itself is a mixture of Portland cement, water and aggregates comprising sand and gravel or crushed stone. In traditional work sites, each of these materials is procured separately and mixed in specified proportions at site to make concrete. Ready Mixed Concrete is bought and sold by volume - usually expressed in cubic meters. RMC can be custom-made to suit different applications. Table 2.4: Mix design adopted at RMC plant S.No. GRADE

SAND

CEMENT

WATER

GRIT

GRIT

(10mm)

(20mm)

ADMIXTURE

2

M-15

626.00

310.00

169.88

627.00

627.00

0.00

3

M-20

630.00

350.00

189.00

579.25

579.25

0.00

4

M-25

580.35

365.00

169.88

627.30

627.80

4.20

5

M-30

450.00

400.00

172.00

487.00

730.00

0.00

6

M-35

601.70

436.00

174.00

571.00

571.00

3.50

596.00

442.00

179.00

565.00

565.00

4.20

CAP 7

M-35 PILE

8

M-40

465.50 470.00

174.00

632.15

632.15

5.17

9

M-45

414.00 488.00

179.00

599.00

732.00

4.80

Source: RMC plant

20

2.2 Equipments 2.2.1 Batch Mix Plant A concrete plant, also known as a batch plant, is a device that combines various ingredients to form concrete. Some of these inputs include sand, water, aggregate (rocks, gravel, etc.), fly ash, potash, and cement. There are two types of concrete plants: ready mix plants and central mix plants. A concrete plant can have a variety of parts and accessories, including but not limited to mixers (either tilt-up or horizontal or in some cases both), cement batchers, aggregate batchers, conveyors, radial stackers, aggregate bins, cement bins, heaters, chillers, cement silos, batch plant controls, and dust collectors (to minimize environmental pollution). A central mix plant combines some or all of the above ingredients (including water) at a central location. The final product is then transported to the job site. Central mix plants differ from ready mix plants in that they offer the end user a much more consistent product, since all the ingredient mixing is done in a central location and is computer-assisted to ensure uniformity of product. A temporary batch plant is similar to the central batch plant but it can be constructed on a large job site.

21

Fig 2.1 Batch Mix Plant All the feeder bins have pneumatic operated gates. The four bins combined have a storage capacity of 7.5 m³.The gates are radial type for coarse/fine

discharge.

Sand

bin

is

also

provided

with

discharge.

Aggregates are discharged into Gathering Conveyor. Is suspended on 6 load cells as soon as the desired recipe accumulates, gathering conveyor discharges the mix on to the slinger conveyor. Gathering conveyor and slinger conveyor are provided with idler rollers and return rollers. Weighing hopper is mounted on 3 load cells with butterfly valve for discharge. Cement weighing hopper capacity 500 kg is provided with pneumatic vibrator and two inlets for two screw conveyors. Water tank supported on load cells and it has gate with rubber gasket at the bottom. Additives comprise of admixture flask of capacity 10 liters with feeding pump. Cement is fed from SILO to the cement weighing hopper. Temporary storage hopper is provided with vibrator and it is utilized for holding the batch of 4 aggregates before feeding into the mixture Pan Type Mixture comes in capacity of 1 m³ and is fixed on the basic 22

structure of the plant. Mixer having 7 arms and shell is reinforced with replaceable high wear resistance NI hard liners. The aggregates, cement, water ad additives are discharged to the Pan Mixer. After proper and homogenous mixing the batch is ready to be discharged by hydraulic system. Fully computerized cabin with SCADA based controller are a standard on ATLAS DM Series plant. Software which is very user friendly ensures top notch performance. Proxy switches are available for each control panel. Display of the entire process of control parameters is available and provision for printing entire data like-Mix Proportion, Batch Weigh, Total No. of Batches, Sub Total, Gross Total, etc. Preset batch controls the number of batches for Transit Mixer. There is provision to store, edit production details, and mix proportions up to 99 recipes. Auto and manual control can be accessed. Cabin is fabricated with M. S. Structured frame and insulated by wood. Strategic location of seat ensures complete view of the plant. 2.2.2 Transit Mixer Transit Mixer are made to transport and mix concrete from a plant to the construction yard more modern plants load the truck with 'Ready Mixed' concrete. With this process, the material has already been mixed, and then is loaded into the truck. The ready mix truck maintains the material's liquid state, through agitation, or turning of the drum, until delivery. The interior of the drum on a concrete truck is fitted with a spiral blade. In one rotational direction, the concrete is pushed deeper into the drum. This is the direction the drum is rotated while the concrete is being transported to the building site. This is known as ‘charging’ the mixer. When the drum rotates in the other direction.

23

2.2.3 Post Tensioning 2.2.3.1 Duct Corrugated plastic duct (Figure 2.2) to be completely embedded in concrete

should

be

constructed

from

either

polyethylene

or

polypropylene. The minimum acceptable radius of curvature should be established by the duct supplier according to standard test methods. Polyethylene duct should be fabricated from resins meeting or exceeding the requirements of Indian Specification The duct should have a minimum material thickness of 2.0 mm + 0.25 mm. Ducts should have a white coating on the outside or should be of white material with ultraviolet stabilizers.

Fig2.2 Corrugated Plastic Duct 2.2.3.2 Bearing Plate A basic bearing plate is a flat plate bearing directly against concrete. Covered by this definition are square, rectangular, or round plates, sheared or torch cut from readily available steel plate. Basic bearing plates are used in conjunction with galvanized sheet metal or plastic

24

trumpets to transition from the strand spacing in the wedge plate to the duct.

Fig 2.3: Bearing Plate 2.2.3.3 Wedges Wedge performance is critical to the proper anchoring of strands. Different wedges have been developed for particular systems and applications such that there is no single standard wedge. However, all are similar. The length is at least 2.5 times the strand diameter, with a 5° to 7° wedge angle and serrated teeth for gripping the strand. They are of case-hardened low carbon or alloy steel. A wedge assembly typically has 2 or 3 part wedges with a spring wire retainer clip in a groove around the thick end. Wedges are case hardened with a ductile core, in order to bite into the strand and conform to the irregularity between the strand and wedge hole. In so doing, the surface may crack. This is normally acceptable and does not affect performance so long as wedges do not break completely into separate pieces. Often, it is only the portion outside the retainer ring that cracks Wedges and Strand-Wedge Connection Wedge performance is 25

critical to the proper anchoring of strands. Different wedges have been developed for particular systems and applications such that there is no single standard wedge. However, all are similar. Wedges are case hardened with a ductile core, in order to bite into the strand and conform to the irregularity between the strand and wedge hole. In so doing, the surface may crack. This is normally acceptable and does not affect performance so long as wedges do not break completely into separate pieces. Often, it is only the portion outside the retainer ring that cracks.

Fig 2.4 Arrangement of wedges and bearing plate 2.2.3.4 Strands Uncoated stress relieved low relaxation seven ply strands. The seven wire strand shall have a centre wire at least 14 percent greater in diameter than the surrounding wires enclosed tightly by six helically placed outer wires with a uniform length of lay of at least 12 times but not more than 16 times of the nominal diameter of the strand. The length of lay for the two and three wire strands shall be uniform throughout and shall be 24 to 36 times the diameter of element wire. The wires in the strand shall be so formed that they shall not unravel when the strand is cut and they shall 26

not fly out of position when the strand is cut without seizing. After stranding, all strands shall be subjected to a stress-relieving. Stress relieving shall be carried out as a continuous process on a length of strand by uncoiling and running through any suitable form of heating to produce the prescribed mechanical properties. Temper colours, which may result from the stress-relieving operation, shall be considered normal for the finished appearance of the strand.

Fig 2.5: Strands for Post tensioning 2.2.3.5 Jack Multi-Strand Jacks Multi-strand post-tensioning tendons are usually stressed as an entire group, using very large custom made jacks. This ensures that all strands are tensioned together and avoids the risk of trapping an individual strand. Stressing jacks are generally of the center-hole type i.e. tendons pass through a hole in the middle and are attached at the rear of the jack (Figure 2.6). Post-stressing jacks must be very accurate which is difficult to achieve. Stressing jacks have more wearing surface and packing than a conventional jack of the same capacity. This, and the necessity of a long jack stroke, increases the potential for variations in the accuracy of 27

the applied force. Other factors that affect the accuracy and efficiency of stressing jacks are: use of dirty oil, exposure of the system to dust or grit, eccentric loading, type of packing, ram position, oil temperature, hydraulic valves, ram and packing maintenance, and readout equipment.

Fig 2.6: Post tensioning jack 2.2.3.6 Master Gauge The master gauge measures hydraulic pressures accurately. The load cell operates

on

the

principle

that

changing

pressure

results

in

a

corresponding change in electrical resistance. The readouts are made with a so-called Transducer Strain Indicator. Gauge readings should not be taken while the ram is retracting or in a static condition as hysteresis will likely result in erroneous values. The calibration curves and master gauge readings are only valid when the ram is extending. If there is any indication of damage to the gauge, the stressing system should be checked with the master gauge. For this

28

reason, the master gauge should be kept locked away in a safe place so that it is always in good working order.

2.2.4 Grouting 2.2.4.1 Mixer The mixer should be capable of continuous mechanical mixing to produce a homogeneous, stable, grout free of lumps or un-dispersed material that it supplies continuously to the pump. Mixers are of two main types: vane (or paddle) mixers with a speed of about 1,000 rpm or high- speed shear (colloidal) mixers with a speed of about 1,500 rpm. The high speed mixer distributes cement more uniformly, improves bleed characteristics and minimizes cement lumps. A high-speed mixer is recommended for pre-bagged grouts.

2.2.4.2 Storage Hopper and Screen Most grouting equipment has a mixing (blending) tank which discharges through a screen into a storage hopper or tank mounted over the grout pump (Figure 2.7). The storage hopper should also have a mixing rotor to keep the grout agitated for continuous use and should be kept partially full at all times. The screen should contain openings of 3mm maximum size to screen lumps from the mix. The screen should be inspected periodically. If lumps of cement remain on the screen, then the mix is not suitable.

29

Fig 2.7: Grout Mixing and Pumping Equipment

2.2.4.3 Grout Pump Grout pumps should be of the positive displacement type and able to maintain an outlet pressure of at least 1MPa (145psi) with little variation.

The pump, hoses and connections should be able to

maintain pressure on completely grouted ducts. A shut-off valve should be installed in the line so that it can be closed off under pressure, as necessary.

Pumps with a variable output capability are adaptable to delivery demands of different duct diameters or to group grouting. However, the grouting pressure should be limited to help prevent blow-outs in the equipment, protect operators, prevent excessive segregation or bleed and prevent possible splitting of concrete by over-pressurizing the ducts. Pumps should have a system for re-circulating the grout when pumping is 30

not in progress and should have seals to prevent oil, air or other foreign substance entering the grout or prevent loss of grout or water. At the pump, grout piping should incorporate a sampling tee with a stop valve. The number of bends and changes in size should be minimized. 2.2.4.4 Pressure Gauge A pressure gage with a full scale reading of not more than 2MPa (300 psi) should be attached between the pump outlet and duct inlet. For short lengths (say less than about 10m (30 feet) of grout hose, the gauge may be placed near the pump - for long lengths, at the inlet. For hose lengths over 30m (100 ft), a gage near the pump and one at the inlet may help identify whether sudden pressure build-ups are in the hoses or the ducts. 2.2.4.5 Hoses The diameter and pressure rating of hoses should be compatible with the pump and anticipated maximum pressures. All hoses should be firmly connected to pump outlets, pipes and inlets. It is recommended that grout hoses be at least 20mm inside diameter for lengths up to about 30m (100 ft) and that a reduction in size at connectors be avoided. Also, narrow openings should be avoided. Both can lead to pressure build-up and possible risk of blockage. 2.2.5 Auto Level An Auto Level machine is the equipment used for all surveying and engineering level applications. They are suitable for obtaining accurate levels during surveys even if the ground is not levelled. For this, an automatic

level

comes

complete

with

an

internal

compensator

mechanism which is a swinging prism. When this mechanism is set close to level, it automatically removes any remaining variation from 31

level. This reduces the requirement to set the instrument truly level even when it is a dumpy or tilting level. It is, therefore, a self-levelling instruments designed by auto level manufacturers for accuracy, ease of operation and rugged dependability. Auto level is now the preferred instrument on building sites, construction and surveying due to ease of use and rapid setup time. They also give maximum portability. Most of the auto levels are supplied with aluminium telescopic tripod stand. With the rising popularity of auto levels for surveying and other engineering application, the auto level manufacturers have included many useful features in today's automatic levels. The popular features of any auto level include: 

Most of the auto levels are provided with aluminum telescopic tripod stand.



They are rigidly constructed and ensure accuracy for years under severe conditions.



Available in various types of models.



They can be set up very easily.



Includes hard shell carrying case with dual latches, plumb bob, Allen wrench, adjusting pin, and instruction manual.



Ensures accurate leveling.



The equipment has easy adjusting features.



They are portable.

Functions of Auto Level Instrument Auto level has dominated the most of the market due to the useful features they provide for surveying and engineering work. Some of the important functions performed by an auto level include: 

Conducting

research

work

smoothly

conditions. 

Ensuring accuracy to the test performed. 32

in

extreme

weather



Making telescopic magnification possible through the apparatus.

Applications of Auto Level Instrument Auto Level equipment is mainly used to obtain accurate leveling while surveying, engineering and other such works. Some of the applications of auto level include: 

Excavation



Optical Surveys



Topographic Surveys



Construction (Buildings, Roadways, etc.)



Mapping

2.2.6 Jacks The adjustable base plate stirrup heads provide a method of adjustment which can be used at either the top or bottom of a scaffold support structure. It is in conjunction with foreheads and adapter and can accept the full loading capacity of cup lock when fully braced.

Fig 2.8: Adjustable Stirrup Head Range of adjustable stirrup heads available with us come in standard sizes of: 32 mm diameter, 225 mm adjustment 35 mm diameter, 350 mm adjustment 35 mm diameter, 450 mm adjustment

33

Chapte r

3

STRUCTURAL COMPONENT

3.1 Sub-Structure 3.1.1 Foundation Pile Foundation A deep foundation is a type of foundation distinguished from shallow foundations by the depth they are embedded into the ground. There are many reasons a geotechnical engineer would recommend a deep foundation over a shallow foundation, but some of the common reasons are very large design loads. Deep foundations can be installed by either driving them into the ground or drilling a shaft and filling it with concrete, mass or reinforced. They are also called as caissons, drilled shafts, drilled piers, Cast-in-drilled-hole piles (CIDH piles) or Cast-in-Situ piles. Rotary boring techniques offer larger diameter piles than any other piling method and permit pile construction through particularly dense or hard strata. Construction methods depend on the geology of the site. In particular, whether boring is to be undertaken in 'dry' ground conditions or through water-logged but stable strata i.e. 'wet boring'. Boring is done until the hard rock or soft rock layer is reached in the case of end bearing piles. If the boring machine is not equipped with a rock auger, then socketing of the hard rock layer is done with the help of a heavy chisel which is dropped from a height of about 1.5 m(depends on the weight of the chisel and design requirements) by 34

suspending it from a tripod stand attached to a winch crane. The socketing is carried out until the desired depth within the rock layer has been attained. Usually, the required depth within the rock layer is considered to be equal to the diameter of the pile in hard rock layers and is taken to be equal to 2.5 times the diameter of the pile in soft rock layers. 'Dry' boring methods employ the use of a temporary casing to seal the pile bore through water-bearing or unstable strata overlying suitable stable material. Upon reaching the design depth, a reinforcing cage is introduced; concrete is poured in the bore and brought up to the required level. The casing can be withdrawn or left in situ. 'Wet' boring also employs a temporary casing through unstable ground and is used when the pile bore cannot be sealed against water ingress. Boring is then undertaken using a digging bucket to drill through the underlying soils to design depth. The reinforcing cage is lowered into the bore and concrete is placed by tremmie pipe, following which, extraction of the temporary casing takes place. The reinforcement cage may need to be lapped with another cage if the depth of the pile exceeds 12m as that is the standard length of reinforcement bars of diameter 16mm and above. In some cases there may be a need to employ drilling fluids (such as bentonite suspension) in order to maintain a stable shaft. Rotary auger piles are available in diameters from 350 mm to 2400 mm or even larger and using these techniques, pile lengths of beyond 50m can be achieved. Such piles commonly fail due to the collapse of the walls of the shaft resulting in the formation of a reduced section which may not be able to bear the loads for which it had been designed. Hence at least a third of piles in projects with a large number of piles are tested for 35

uniformity using a ‘Pile Integrity Tester’. This test relies on the manner in which low intensity shock waves are affected as they pass through the pile and are reflected to judge the uniformity and integrity of the pile. A pile failing the integrity test is then subjected to a pile load test. 3.1.2 Pile cap Foundations relying on driven piles often have groups of piles connected by a pile cap (a large concrete block into which the heads of the piles are embedded) to distribute loads which are larger than one pile can bear. Pile caps and isolated piles are typically connected with grade beams to tie the foundation elements together; lighter structural elements bear on the grade beams while heavier elements bear directly on the pile cap. Sequence for construction of pile cap 3.1.2.1 Excavation At road locations the pit shall be excavated to the dimensions providing working space all around the pile cap. Proper side slope or shoring shall be provided depending upon the suitability of the soil found in the area.

The last 200mm excavation shall be carried out

manually. 3.1.2.2 Fixing of shuttering and formwork After excavation the proper shuttering is fixed with supporting form work according to drawing and maintaining the size of pile cap. 3.1.2.3 Removal of laitance After excavation the laitance of the piles shall be removed by using pneumatic jack hammer minimum sever days after casting of pile or manually minimum. Three days after casting of pile. The top of pile after striping shall project 300m above the cut-off level. 36

Fig.3.1: Removal of Laitance 3.1.2.4 P.C.C Laying After leveling the bottom, the pit shall be watered to keep the soil moist, mix concrete used as a P.C.C and transported for batching plant to the P.C.C Laying site through transit mixer. The concrete shall be directly poured by chute & shall be spread, leveled manually to the 150 mm thickness. 3.1.2.5 Pile cap reinforcement The reinforcement bar shall be cut in a proper length and bend according to bar bending schedule. The bar shall be provided with inhibitor treatment by applying inhibitor solution mixed with cement in a ration of 600ml: 1 kg of cement and stacked for drying under shed for 24 hrs. The reinforcement bar is fixed in a proper location according to drawing over the P.C.C and tied with 1mm diameter Galvanizing iron binding wire. 75 mm clear cover is provided at the bottom both side 37

and upper face of rebar cage. The vertical reinforcement of pier is also tied with pile cap reinforcement and crash barrier reinforcement also tied. Refer drawing for Dimension Details of Pile Foundation & Pile cap. 3.1.3 Piers Piers are constructed above the footings. They provide vertical support to the bridge superstructure Pier construction begins once the footings are in place. The forms are typically constructed to cast/build segments of the pier vertically, and moving the forms upward as the pier construction takes place. Many different shapes of the piers are possible; the most economical shape would have a consistent cross section. The size and frequency of piers depends on the type of super structure and spans they are supporting. Concrete is the most likely construction material to be used. Twin Piers are constructed to facilitate balanced cantilever construction technique. Steel form used to construct oblong pier shape, Steel rebar extending from pile cap is continued in piers up to pier cap. Steel forms are used to place around rebar cage to cast concrete. 3.1.3.1 Reinforcement Fabricated

and

tie

the

pier

reinforcement

cut

and

bend

the

reinforcement bar for tie reinforcement according to drawing bar bending Schedule. The bar shall be provided with inhibitor treatment by applying inhibitor solution mixed with cement in ratio of 600ml: 1kg of cement and stacked for drying under shed form 24 hrs. Tie reinforcement tied with the vertical reinforcement through galvanized iron binding wire according to drawing.

38

3.1.3.2 Shuttering and Formwork for Pier Shuttering and form of pier formwork fixed the pier shuttering and form proper formwork is fixed form supporting the pier shuttering according to drawing. 3.1.3.3 Concreting Completion of shuttering concreting would be started with the help of concrete pump. Before pouring concrete we check the slump. The range of slump is 100 –120mm. The drop height of the concrete should not more than 1.5m. At one time we can concrete max 2m and compacted by needle vibrator 60mm full of concreting should be done continuously one pour. Total concreting time 6-8 hrs. In the pier 5-6 layer of concrete should be sufficient. The max range of concrete temperature is 40°C. 3.1.3.4 Curing Curing of pier concrete is done with the help of wet jute cloth for min 7 days.

3.2 Super Structure 3.2.1 Pier Cap Sequence work for pier cap 3.2.1.1 Scaffolding Scaffolding is a temporary structure used to support people and material in the construction or repair of buildings and other large structures. It is usually a modular system of metal pipes or tubes. The key elements of a scaffold are standards, ledgers and transoms. The standards, also called uprights, are the vertical tubes that transfer the entire mass of the structure to the ground where they rest on a square concrete base plate to spread the load. The base plate has a shank in its centre to hold the tube and is sometimes pinned to a sole board. 39

Ledgers are horizontal tubes which connect between the standards. Transoms rest upon the ledgers at right angles. Main transoms are placed next to the standards. The height of strands and ledger available are 0.5m, 1m, 1.5m, 2m, 2.5m, 3m, 4m etc.

Fig.3.2: Scaffolding for pier cap 3.2.1.2 Level transferred to pier After completion of pier, the levels as per drawings are transferred to the pier with the help of auto level (see appendix IV) the bottom level of pier cap is marked on the pier and scaffolding is erected up to that level, some space is left for bottom shutter plat and IS Medium Beam 125 to support the dead load of pier cap before it attains its full strength. Adjustable stirrup head are placed between the ISMB 125 and top of scaffolding to adjust the top level of bottom shutter plate.

40

Fig 3.3: Arrangement of shutter plate, ISMB, Adjustable stirrup head After fixing of bottom shutter plate the top level of bottom shutter plate are checked by auto level (see appendix IV) the top surface of shutter plate should be in a same level, so that the bottom of pier cap is to be casted should be smooth. 3.2.1.3 Reinforcement The reinforcement bar is to be placed as per drawings and bar bending schedule. Rebar cages are fabricated either on the project site commonly with the help of hydraulic benders and shears, however for small or custom work a tool known as a Hickey or hand rebar bender, is sufficient. The rebars are placed by rod busters or concrete reinforcing ironworkers with bar supports separating the rebar from the concrete forms to establish concrete cover and ensure that proper embedment is achieved. The rebars in the cages are connected by welding or tying wires. Welding can reduce the fatigue life of the rebar, and as a result rebar cages are normally tied together with wire. Besides fatigue concerns welding rebar has become less common in developed countries due to the high labor costs of certified welders.

41

There are different types of ties used for securing rebars. It is better to use two twisted strands of annealed 0.9 to 1.6 mm diameter wires. 3.2.1.4 Concreting Concreting at a higher altitude is a difficult task, so concrete pump is required concrete pump is attached to a truck. It is known as a trailermounted boom concrete pump because it uses a remote-controlled articulating robotic arm (called a boom) to place concrete with pinpoint accuracy. Boom pumps are used on most of the larger construction projects as they are capable of pumping at very high volumes and because of the labour saving nature of the placing boom. They are a revolutionary alternative to truck-mounted concrete pumps. The bends in the pipes conveying concrete from the pump should be minimal in order to avoid losses. In addition, these should not be sharp. Each 10o bend is equivalent to an extra length of pipe of 1 m. The pipe diameter should be at least 3 times the maximum aggregate size. Large aggregates can especially tend to get blocked near the bends. The economy of pumping depends on the number of interruptions. Each time, the priming of the pipes using mortar is required (0.25 m3/100 m of 6 inch pipe), and the pipe also has to be cleaned. Aluminum pipes should be avoided, as the Al reacts with alkalis in the cement, and leads to the evolution of hydrogen gas. These gases tend to introduce voids in the concrete, which reduce the efficiency of pumping. Pumping enables concreting of inaccessible areas. Moreover, the direct conveyance of concrete from the truck to formwork can avoid double handling of the concrete.

42

Requirements for pumped concrete 

Concrete mixture should neither be too harsh nor too sticky; also, neither too dry nor too wet.



A slump between 50 and 150 mm is recommended (note that pumping induces partial compaction, so the slump at delivery point may be decreased).



If the water content in the mixture is low, the coarse particles would exert pressure on the pipe walls. Friction is minimized at the correct water contents. The presence of a lubricating film of mortar at the walls of the pipe also greatly reduces the friction.



High cement content in concrete is generally beneficial for pumping.



Water is the only pump able component in the concrete, and transmits the pressure on to the other components.

Two types of blockage to efficient pumping could occur: 

Water can escape from the mixture if the voids are not small enough; this implies that closely packed fines would be needed in the mixture to avoid any segregation. The pressure at which segregation occurs must be greater than that needed to pump concrete.



When the fines content is too high, there could be too much frictional resistance offered by the pipe. The first type of blockage occurs in irregular or gap-graded normal strength mixtures, while the second type occurs in high strength mixtures with fillers. In order to avoid these two types of failure, the mixture should be proportioned appropriately.



Other mixture factors that could affect pumping are the cement content, shape of aggregate, presence of admixtures such as 43

pumping aids or air entrainment. Air entrainment is helpful in moderate amounts, but too much air can make pumping very inefficient. 

When flowing concrete is being pumped, an over-cohesive mixture with high sand content is recommended. For lightweight aggregate concrete, pumping can fill up the voids in the aggregate with water, making the mixture dry.

Fig.3.4: Boom placer concreting pier cap 3.2.1.5 Compaction It is important that concrete be vibrated at the correct frequency to fluidise the mix, to coat the aggregate with cement paste and to release trapped air. The operating frequency of internal vibrators may

44

be less than specified values, which may have been measured with the vibrator operating in air. A reduction in frequency results in an energy reduction, which in turn reduces the effective compaction area. It is important to introduce the vibrator in a systematic way, so that the compaction areas overlap and all the concrete is compacted. An internal vibrator with an electric motor and electronic speed control has been developed. This gives controlled energy input and has the added benefit of a lighter, more flexible cable.

Fig.3.5: Needle vibrator for Compaction 3.2.1.7 Finishing When the concrete compaction and screeding is done, the slab is roughly floated with a trowel to give a smooth surface. After floating, slab is left to set hard. Free water (bleed water) will rise to the surface of the slab after it is leveled. Wait until the surface water dries before doing the final float or trowel finishing. On a cold day the bleed water may have to be dragged off by pulling a rope or hose over the surface. Never spread dry cement or sand over the slab to absorb the bleed water as this will make the finished surface weak and dusty. Wood or steel hand-floats and trowels do a good job too; the whole surface should be worked over twice. Save finishing time by finishing the 45

girder only to the standard needed for the type of finish to be used, the top surface is finished smooth. 3.2.1.7 Curing Approved curing compounds may be used in lieu of moist curing with the permission of the engineer-in charge. Such compounds shall be applied to all exposed surfaces of the concrete as soon as possible after the concrete has set. Water covering closely the concrete surface may also be used to provide effective barrier against evaporation. For the concrete containing portland cement, portland slag cement or mineral admixture, period of curing may be increased.

Fig.3.6: curing of pier cap 3.2.2 Bearings POT bearings for incrementally launched bridges have a dual function. First, they provide low friction sliding surfaces over piers as the deck is launched during construction. Thereafter, they become permanent bearings for the completed bridge. A POT bearing serving both functions is shown in the picture above. During construction, a fixing device avoids relative movement between sliding plate and pot cylinder. POT bearing for bridge the sliding plate is supplied with a 46

second stainless steel sheet on top. Inserting neoprene-teflon pads between deck and bearings allows the launching operation to be carried out. Pads, second stainless steel sheet and fixing device are removed after launching. To achieve this, the deck is lifted by means of hydraulic jacks placed on top of the piers. Once this operation is achieved, the deck is lowered to its final position, the jacks are removed and the sliding plate is connected to a previously embedded steel

plate

in

the

deck.

Finally,

the

fixing

devices

used

for

transportation are released, thus the bearing is in its final service position. For the correct design of these bearings, it is very important to know the loads during launching, because, they have major influence in the actual length and thickness of the sliding plates. Although the cost of this type of bearing is higher than the standard ones, their use represents a saving for the job because:  Temporary launching bearings are not required  Demolition and replacement of the temporary bearings by permanent ones, is costly and time consuming therefore avoided

Fig. 3.7: POT bearings 47

Site Installation 3.2.2.1 Preparation of the piers Build the piers leaving on them the required recesses according to the dimensions indicated on the drawings. Pedestal reinforcement is anchored during the formation of mesh of reinforcement of pier cap.

Fig. 3.8: Reinforcement for pedestal 3.2.2.2 Levelling of bearings

Fig. 3.9: Plan view

Fig. 3.10: Elevation

48

Place the pot bearing in its position levelling it with Steel wedges. It is important to ensure that the X-axis of the bearing is aligned in the longitudinal direction of the bridge and that the X and Y directions are accurately horizontal. For bearings allowing horizontal displacements it should be checked that the arrow painted on the slide plate is pointing in the correct direction. Install the form for grouting the space between pier and pot bearing. Grout the space between pier and pot bearing. Fill in the recesses checking that the level is the correct. 3.2.2.3. Formwork for diaphragm wall The formwork of the deck is placed embedding the upper dowels of the bearing

Fig. 3.11: Formwork for Diaphragm wall 3.2.2.4 Removal of fixing plates Once the formwork has been removed, the bearing is definitively installed. Remove the lateral fixing plates of the bearing in order to allow its free movement.

49

Fig. 3.12: Removal of fixing plates 3.2.2.5 Types of Bearing for joints of girder on pier cap Fixed joint

Fig. 3.13: Bearing for fixed joint

50

Expansion joint

Fig. 3.14: Bearing for expansion joint

Free joint

Fig.3.15: Bearing for free joint

51

3.2.3 Precast Girder 3.2.3.1 P.C.C The plane cement concrete strip of cement mix 1:6 is laid and a strip of length and breadth about 1.4 times than that of dimension of precast girder and thickness of 20 mm. A constant level line is maintained throughout the strip by help of auto level and its top surface is leveled by flat trowels. 3.2.3.2. Runner At some intermediate distance C shaped steels bars of diameter 16 mm and length 1.2 times width of precast girder are placed across the length of P.C.C strip. Runners are provided to stop skidding the shuttering plates in outward direction due to force produced by concrete placement and compaction of concrete.

Fig 3.16: P.C.C for casting girder 3.2.3.3 Flats Steel plates of 5 mm thick are placed over the P.C.C strip to provide smooth bottom of precast girder.

52

3.2.3.4 Reinforcement Steel reinforcements are used, generally, in the form of bars of circular cross section in concrete structure. They are like a skeleton in human body. Plain concrete without steel or any other reinforcement is strong in compression but weak in tension. Steel is one of the best forms of reinforcements, to take care of those stresses and to strengthen concrete to bear all kinds of loads. Mild steel bars conforming to IS: 432 (Part I) and Cold-worked steel high strength deformed bars conforming to IS: 1786 (grade Fe 415 and grade Fe 500, where 415 and 500 indicate yield stresses 415 N/mm2 and 500 N/mm2 respectively) are commonly used. Grade Fe 415 is being used most commonly nowadays. This has limited the use of plain mild steel bars because of higher yield stress and bond strength resulting in saving of steel quantity. Some companies have brought thermo mechanically treated (TMT) and corrosion resistant steel (CRS) bars with added features. Bars range in diameter from 6 to 50 mm. Cold worked steel high strength deformed bars start from 8 mm diameter. For general house constructions, bars of diameter 6 to 20 mm are used. Transverse reinforcements are very important. They not only take care of structural requirements but also help main reinforcements to remain in desired position. They play a very significant role while abrupt changes or reversal of stresses like earthquake etc. They should be closely spaced as per the drawing and properly tied to the main/longitudinal reinforcement.

53

Terms used in Reinforcement 3.2.3.5 Bar-bending-schedule Bar-bending-schedule is the schedule of reinforcement bars prepared in advance before cutting and bending of rebars. This schedule contains all details of size, shape and dimension of rebars to be cut. (Refer Appendix II). 3.2.3.6 Lap length Lap length is the length overlap of bars tied to extend the reinforcement length. Lap length about 50 times the diameter of the bar is considered safe. Laps of neighboring bar lengths should be staggered and should not be provided at one level/line. At one cross section, a maximum of 50% bars should be lapped. In case, required lap length is not available at junction because of space and other constraints, bars can be joined with couplers or welded (with correct choice of method of welding). 3.2.3.7 Anchorage length This is the additional length of steel of one structure required to be inserted in other at the junction. For example, main bars of beam in column at beam column junction, column bars in footing etc. The length requirement is similar to the lap length mentioned in previous question or as per the design instructions. 3.2.3.8 Cover block Cover blocks are placed to prevent the steel rods from touching the shuttering plates and thereby providing a minimum cover and fix the reinforcements as per the design drawings. Sometimes it is commonly seen that the cover gets misplaced during the concreting activity. To prevent this, tying of cover with steel bars using thin steel wires called binding wires (projected from cover surface and placed during making 54

or casting of cover blocks) is recommended. Covers should be made of cement sand mortar (1:3). Ideally, cover should have strength similar to the surrounding concrete, with the least perimeter so that chances of water to penetrate through periphery will be minimized. Provision of minimum covers as per the Indian standards for durability of the whole structure should be ensured. Shape of the cover blocks could be cubical or cylindrical. However, cover indicates thickness of the cover block. Normally, cubical cover blocks are used. As a thumb rule, minimum cover of 2” in footings, 1.5” in columns and 1” for other structures may be ensured. Table 3.1: Minimum cover to reinforcement Structural element Cover to reinforcement (mm) Footings

40

Columns

40

Slabs

15

Beams

25

Retaining wall

25 for earth face 20 for other face

3.2.3.9 Things to Note Reinforcement should be free from loose rust, oil paints, mud etc. it should be cut, bent and fixed properly. The reinforcement shall be placed and maintained in position by providing proper cover blocks, spacers, supporting bars, laps etc. Reinforcements shall be placed and tied such that concrete placement is possible without segregation, and compaction possible by an immersion vibrator.

55

For any steel reinforcement bar, weight per running meter is equal to d2/162 kg, where d is diameter of the bar in mm. For example, 10 mm diameter bar will weigh 10×10/162 = 0.617 kg/m. Three types of bars were used in reinforcement of a slab. These include straight bars, crank bar and an extra bar. The main steel is placed in which the straight steel is binded first, then the crank steel is placed and extra steel is placed in the end. The extra steel comes over the support while crank is encountered at distance of one fourth of span from the supports. For providing nominal cover to the steel in beam, cover blocks were used which were made of concrete and were casted with a thin steel wire

in

the

center

which

projects

outward.

These

keep

the

reinforcement at a distance from bottom of shuttering. For maintaining the gap between the main steel and the distribution steel, steel chairs are placed between them. For details of reinforcement refer to drawing no 3.1.1. Profiling Duct Installation 3.2.3.10 Alignment Correct duct alignment and profile is of paramount importance for proper functioning of a post-tensioning tendon, whether that tendon is internal or external to concrete. Duct alignment and profile should be clearly and sufficiently defined on the plans and approved shop drawings by dimensions to tangent points, radii, angles and offsets to fixed surfaces or established reference lines and by entry and exit locations

and

angles

at

anchorage

or

intermediate

bulkheads.

Alignment, spacing, clearance and details should be in accordance with Indian Specifications.

56

General recommendations for fabrication are that ducts should be:  Installed with correct profile (line and level) within specified tolerances.  Tied and properly supported at frequent intervals.  Connected with positively sealed couplings between pieces of duct and between ducts and anchors.  Aligned with sealed couplers at temporary bulkheads.  Positively sealed at connections made on-site and in cast-inplace splice joints.  The elevations and alignments of ducts should be carefully checked.  Installed to connect correct duct location in bulkhead with correct duct location in matchcast segment.  Correctly aligned with respect to the orientation of the segment in the casting cell and the direction of erection.  Elevations and alignments of longitudinal and transverse ducts

should be carefully checked.

Fig. 3.17: Profiling of Ducts 57

3.2.3.11 Local Zone Reinforcement Regardless

of

the

type

of

anchor,

it

is

essential

to

provide

reinforcement in the local anchor zone – this is the region directly behind the anchor bearing plate(s). For longitudinal strand, tendons comprise a spiral shape (Fig 3.18). Local zone reinforcement should be placed as close as possible (i.e.12mm maximum) to the main anchor plate in all applications. A series of relatively rectangular stirrups is normally provided to reinforce the general anchor zone (region around and beyond the local zone) until the local anchor force has dispersed to the full effective depth of the section. Typically, for an I-girder, this extends over a length approximately equal to the depth of the beam from the anchor. Local anchor zones for transverse deck slab tendons anchored in the relatively shallow depth at the edge of segments are most effectively reinforced by multiple-U shaped bars placed in alternating up and down arrangement, beginning very close to the anchor plate. This arrangement has been found to be very effective for intercepting potential cracks that might originate at the top or bottom corner of the anchor bearing plate and travel diagonally through the adjacent surface – apart from the classical splitting stress along the line of the tendon itself.

Fig. 3.18: General and Local Anchor Zone in end of I-Girder

58

3.2.3.12 Shuttering Shuttering or formwork is the term used for temporary timber, plywood, metal or other material used to provide support to wet concrete mix till it gets strength for self support. It provides supports to horizontal, vertical and inclined surfaces or also provides support to cast concrete according to required shape and size. The formwork also produces desired finish concrete surface. Shuttering or formwork should be strong enough to support the weight of wet concrete mix and the pressure for placing and compacting concrete inside or on the top of form work/shuttering. It should be rigid to prevent any deflection in surface after laying cement concrete and be also sufficient tight to prevent loss of water and mortar form cement concrete. Shuttering should be easy in handling, erection at site and easy to remove when cement concrete is sufficient hard. The shuttering plates are pre designed as per dimensions from drawing. The plates are cleaned and lubricating oil is polished on the surface of plate in contact with concrete. A layer of liquid proofing material is applied between the two plates the plates are bolted together till the settling of concrete. Shuttering is supported by the manual jacks. Alignment of Shuttering

Fig. 3.19: Shuttering of girder 59

When shuttering plates are fixed they are not vertical. Thus the final shape of girder will not be smooth and linear. So the alignment of shuttering is to be done. A thread is tied along the length of girder at a fixed distance (x) outward from shuttering plates, at the last plate near to end face of girder a plumb bob is placed and verticality of the plates is checked by measuring the distance of thread of plumb bob from plate, this distance should be same to the distance (x), the distance is checked both at top of plate and bottom of plate, if distance is larger than that of fixed at bottom of plate then upper jack supporting the plate is tightened or vice versa, this procedure is repeated on every plate to check the alignment of plate. Fixing of anchor cone Anchor Cone is made of steel. It is a steel guide embedded in concrete, while providing shuttering on face of girder, one end of anchor cone is fixed on shuttering plate through bolts and at other end of it, sheathing is mounted. It is covered by the spiral rebar. It provides a firm base to jack for post tensioning and protect concrete from bursting.

Fig. 3.20: Anchor cone

60

3.2.3.13 Concreting Concrete is ordered by strength-grade and slump. Never use concrete less than M20 grade (20 MPa of strength, with 20 mm nominal maximum aggregate size and 80 mm slump). The concrete grade used for girder was M45 as per design. Reject the concrete with a slump of more than 100 mm. In fact 80-mm slump is better. It may be slightly harder to work into place, but it can be finished sooner and will shrink less. The slump of concrete is a rough measure of the amount of water in the mix. If water is added the mix will become sloppy and easier to work into place – but the concrete will be weaker, more cracks will be there and have a poor surface finish. For this reason no water should be added to concrete during the placement and finishing operations. Place each batch of concrete next to the previous batch. Start from one end and work along the girder making sure that each new batch is well mixed into the batch before. Do not let concrete free-fall more than 1m from a chute, pipe or bucket when it is being placed. Level the surface of the concrete with a screeding board. It is important to move the screeding board with a sawing and chopping motion as this helps to compact the concrete. 3.2.3.14 Compaction A needle vibrator is used to compact the concrete. Poke the vibrator into the concrete every half m over the length of the beam and hold it in place until the concrete settles and bubbles stop rising to the surface. Hold the vibrator straight up and be careful not to move the steel reinforcement, or damage the underlay or formwork. Curing should be done. 3.2.3.15 Post-tensioning Principle of Post-tensioning The function of post-tensioning is to place the concrete structure under compression in those regions where load causes tensile stress. Tension 61

caused by the load will first have to cancel the compression induced by post-tensioning the before it can crack the concrete. Fig. 3.21 shows a plainly reinforced concrete simple-span beam and fixed cantilever beam cracked under applied load.

Fig. 3.21: Reinforced concrete beam under load By placing the post-tensioning low in the simple-span beam and high in the cantilever beam, compression is induced in the tension zones; creating upward camber. Fig. 3.22 shows the two post-tensioned beams after loads have been applied. The loads cause both the simple-span beam and cantilever beam to deflect down, creating tensile stresses in the bottom of the simple-span beam and in top of the cantilever beam. The bridge designer balances the effects of load and post-tensioning in such a way that tension from the loading is compensated by compression induced by the post-tensioning. Tension is eliminated under the combination of the two and tension cracks are prevented. Also, construction materials (concrete and steel) are used more efficiently; optimizing materials, construction cost. Post-tensioning can be applied to concrete members in two ways, by pre-tensioning or post-tensioning. In pre-tensioned members the pre-stressing strands are tensioned against restraining bulkheads before the concrete is cast. After the concrete has been placed, allowed to harden and attain sufficient

62

strength, the strands are released and their force is transferred to the concrete member. Pre-stressing by post-tensioning involves installing and stressing prstressing strand or bar tendons only after the concrete has been placed, hardened and attained a minimum compressive strength for that transfer.

Fig. 3.22: Comparison of reinforced and post-tensioned concrete beams Tendon Installation Multi-strand tendons are the most frequent choice for main longitudinal tendons in bridges. All the strands of one tendon are tensioned together using a multi-strand jack. The sequence in which tendons are stressed and the ends from which they are stressed should be clearly shown on the contract plans or approved shop drawings and must be followed. Anchoring Tendons A bearing plate is fixed having holes equal as no of strands and an anchorage body for anchoring tendons with wedges, having a central passage or bore for the tendon, at least one part or section of which passage widening conically from the inlet end to the outlet end in order to form a seat for wedges, said anchorage body presenting at the inlet end of said passage a projection integral with the remaining part of the 63

body and having also a passage or bore for the tendon to form a holding means for a sealing element surrounding the portion of a tendon near the anchoring body.

Fig. 3.23: Anchor set or wedge set

Jacking Methods When the tendons are very long, losses over the length of the tendon due to friction and wobble become large. Stressing the tendon from the second end results in a higher force in the tendon than if only stressed from one end. Also, for symmetrical tendons two-end stressing becomes effective when the effect of anchor set at the jacking end affects less than half of the tendon (Fig. 3.23). Stressing from the second end should not be done if the calculated elongation is less that the length of the wedge grip. Re-gripping in a portion of the old grip length should be avoided. ‘Two End Stressing’ results in symmetrical stresses, and, in longer tendons, higher stress levels.

64

Fig. 3.24: Stresses along tendon for Two End Stressing

Fig. 3.25: Arrangement of post-tensioning Jack The force required in each tendon is determined by the designer and is given on the approved shop drawings or job stressing manual. Also, the corresponding elongations are predetermined taking into account all losses due to curvature friction, wobble, wedge set, and friction within the anchor and jack, as necessary (refer to Appendices III). For post-tensioning, measurement of elongations serves as a check of the anticipated jacking force primarily given by the gauge pressure and 65

calibration

chart.

The

stressing

operation

should

constantly

be

monitored by an inspector. There are two basic pieces of information that need to be recorded: tendon elongations and gauge pressures. Both will give an indication whether the tendon is stressed to the force required. The gauge pressure is a direct measurement of the force at the jack and the elongation will give an indication how the remainder of the tendon is being stressed. Normally the tendon will be stressed to a predetermined gauge pressure, representing a certain force in the tendon at the stressing end. The elongation measured at this point is compared to the theoretically determined elongation. Measuring Elongations on Strand Tendons When stressing a tendon a certain portion of jack extension will be needed to remove the slack. This gives a false initial elongation that should not be part of the real elongation measurements. For this reason, the first step is to stress the tendon an initial force of approximately 20% of the final force to remove the slack. From this point up to 100% of the required load, the extension of the jack will cause pure elongations of the tendon. At the end of the operation, a correction can be made for the unmeasured portion of the elongation by straight extrapolation. The accuracy of the determination of the elongation obtained during the first step, i.e. tensioning up to 20% of the jacking force, can sometimes be improved by recording elongations at intermediate gauge readings of 40%, 60% and 80% and plotting results on a graph. Ideally, the graph should be a straight line. Intermediate elongations must be recorded if a long tendon has to be stressed using two or more pulls on the jack when the required elongation is greater than the available stroke For short, mono or multi-strand tendons it may suffice to check the elongation for the stressing range between 20% and 100% load against the calculated value for this range. Short tendons are those generally less than about 30m (100 feet) long where the expected elongation is only about 0.2m 66

(8 inches) or less and is easily made with a single, steady and continuous stroke of the jack. Elongation may be measured by the extension of the cylinder beyond the barrel of the jack. However, this is acceptable only if the wedge pull-in of the internal wedges that grip the strand inside the jack is reliably known; it is deducted from the measured extension on the cylinder to give the actual strand elongation. This method is often preferred for convenience. Strand End Cut-off The ends of the strands should only be cut off if the jacking forces and elongations are satisfactory. If there is any doubt that might require verification by a lift-off test or additional jacking, strands should not be cut. Preferably, strands should be trimmed as soon as possible, so that permanent grout caps can be placed over the wedge plate to seal the tendon until grouting. Strands should be cut off at the wedges leaving approximately 12 to 20mm (½” to ¾”) of strand projecting but no greater than that which can be accommodated by any permanent nonmetallic grout cap supplied for installation with the post-tensioning system. Strands should be cut only with an abrasive cutting tool. Under no circumstances should flame cutting be used as the heat can soften the strands and wedges and lead to loss of strands. Recently, plasma cutters have become available; their use should only be with strict inspection and approval of the Engineer. After strand tails have been cut-off, the ends of the tendon should be temporarily protected in an approved manner until the tendon has been grouted. Preferably, a non-metallic (plastic) grout cap should be placed over the strands and wedges. 3.2.3.16 Grouting The purpose of grouting is to provide permanent protection to the post-tensioned steel against corrosion and to develop bond between the post-tensioned cables and the surrounding structural concrete. 67

Grouting shall be carried out as early as possible, but generally not later than two weeks of stressing. Whenever this stipulation cannot be completed

with

for

unavoidable

reasons

adequate

temporary

protection of the cables against corrosion by methods or products, which will not impair the ultimate adherence of the injected grout shall be ensured till grouting. Verification of Post-Tensioning Duct System Prior to Grouting Check for Water and Debris Prior to grouting, tendon ducts, grout inlets and outlets, and anchors, should be examined and a water jet is injected at pressure of 50kg/cm2 to remove debris and water to avoid blockages or dilution. Inlets, Outlets and Connections Connections from grout hose to inlets and outlets should be airtight and free from dirt. Inlets and outlets should be provided with positive shut-offs capable of withstanding the maximum grouting pressure. The required grouting pressure should take into account the pressure head for vertical changes in profile. Appropriate repairs should be made to any damaged inlets and outlets prior to grouting.

Fig. 3.26: Arrangement of grout cap, inlets & outlets

68

Pressure Check of Duct System Prior to grouting, it is recommended that the post-tensioning ducts be tested using compressed air to verify if any duct connections, joints or fittings require sealing or repair. Compressed air should be clean, dry and free from any oil or contaminants. A possible test would be to consider the duct system satisfactory if, after pressurizing to an initial pressure (e.g. 0.7MPa (100 psi)) the pressure loss over five minutes is less than 10% (e.g. 0.07MPa, In any case, it would be necessary to temporarily seal the ends of ducts. This could be done with anchor grout caps. Testing to 0.7MPa (100 psi) before concrete placement, connections and fittings or using a suitable sealant approved by the manufacturer of the PT duct system and acceptable to the Engineer. Leaks at match-cast joints could be sealed by epoxy injection or other acceptable means. In no case should duct tape be used as a seal; however, it may be used to provide temporary support or restraint. Batching and Mixing The proportions in the mix should be based upon the mix approved prior to grouting is begun whether for a mix to be blended on site or for a pre-qualified, pre-bagged grout. Dry powder and pre-bagged grout materials should be batched by weight to an accuracy of ±2%. Water and liquid admixtures may be batched by weight or volume to an accuracy of ±1%. Any water content in any liquid admixtures should be counted towards the quantity of water.

The materials should be mixed to produce a homogeneous grout without excessive temperature rise (limiting up to 10 ºC) or loss of fluid properties (flow cone). The mix should be continuously agitated until it is pumped. Water must not be added to increase fluidity if it has decreased by delayed use of the grout. Typically, the mix time for 69

grout should be in accordance with the qualification trials and generally not more than 4 min for a vane mixer or 2 min for a highspeed shear mixer. Unless otherwise specified by the manufacturer, the constituents may be added as follows:  For a vane mixer: all the water, about 2/3 cementitious material, the admixture and the remaining water.  For a high speed shear (colloidal) mixer: water, admixture and cementitious material. Condensed, dry compacted silica fume should not be added to a mix as it agglomerates and does not blend well, leading to a poor mix. Injection of Grout Pumping Grout pumping methods should ensure complete filling of the ducts and encasement of post tensioning steel. Grout should be pumped in a continuous operation and be ejected from the first, and subsequent outlets, until all visible slugs of water or entrapped air have been removed prior to closing each outlet in turn. At each outlet and final grout cap, pumping should continue until the consistency of the discharged grout is equivalent to that being injected at the inlet. At least 7.5 liters (2 gallons) of good, consistent, quality grout should be discharged through the final anchor and cap before closing them. Limiting Grout Injection Pressures For normal operations grout should be injected at a pressure of less than 0.52 MPa (75psi) at the inlet. Pumping pressures should not exceed 1MPa (145 psi). Although higher pressures than this might be sustained by internal ducts of HDPE or steel or external ducts of steel pipe, higher pressures are not recommended for grouting. Sometimes an initial temporary higher pressure may be needed to mobilize a

70

thixotropic grout, but, once flowing, pumping pressures should be the same as for normal grout. Vacuum Grouting Operation Vacuum grouting generally involves the following activities:  Pressurize void and check for leaks.  Seal leaks (tighten all caps and seal leaks with epoxy or epoxy injection).  Measure the volume of the void to determine the necessary quantity of grout.  Mix sufficient grout for use and for testing, record quantity of mixed grout.  Test the grout using the flow-cone or modified flow-cone method.  Evacuate air from the voids.  Switch valve and inject grout into voids under pressure.  Record quantity of grout remaining and calculate the amount injected.  Seal grout injection inlets.  Clean equipment, area of operations on structure and properly discard unused grout.  Record and report vacuum grouting operations. Sealing of Grout Inlets and Outlets It is recommended that threaded plastic caps be used to seal all grout inlet and outlet pipes and that threaded plugs be installed in anchorages and grout caps once the grout pipe and shut-off valve have been removed (Fig. 3.27). Where an inlet or outlet is permanently recessed

within

the

concrete,

provision

should

be

made

to

accommodate the threaded plastic cap at clear depth of at least 25mm (1”) by means of a formed recess. The recess should be cleaned and completely filled with an approved epoxy material. The surface of the

71

recess should be prepared to receive the epoxy material in accordance with the recommendations of the manufacturer of the epoxy.

Fig. 3.27: Sealing of grout inlets and outlets 3.2.3.17 Erection of girder Stool Fixing

Fig. 3.28: Stool for girder Stools are temporary arrangements for resting of girder on pier cap they are made of high strength steel, they are fixed on pier cap with 72

the help of high strength friction grip bots having gross dia of 22.5 mm, there bottom plate is fixed on pier cap and its top surface has arrangement for adjustment of level below it. Thus the top plate of stool can be adjusted accordingly to required level or chamber of bridge (see Appendix IV). Erection of the precast concrete girders must be done accurately and carefully, as shown on the drawings and in a manner that will prevent damaging the girders.  Contractor must clean the bearing surfaces and the surfaces to be in permanent contact before the members are assembled.  Check the elevations, camber, and girder alignment and ensure that the diaphragms are completely connected. Take profiles of the girder tops so that camber adjustments may be determined with particular emphasis on the differential camber between adjacent girders.  When the girders are satisfactorily erected and approved, ensure that the lifting devices are cut off, all lifting pockets are filled with grout, and lifting holes on exterior girders are filled with grout.  Inspect the girders for cracks, chips or other damage, which may have occurred during erection.  Report any damaged girders noted to the Bridge Project Engineer.  If post-tensioning

of the girders is required, discuss the

procedures and all aspects of the inspection required with the Bridge Project Engineer.

73

Fig. 3.29: Erection of girder 3.2.4 Diaphragm Wall 3.2.4.1 Formwork The formwork shall be designed and constructed so as to remain sufficiently rigid during placing and compaction of concrete, and shall be such as to prevent loss of slurry from the concrete. For further details regarding design, detailing, etc. reference may be made to IS 14687. The tolerances on the shapes, lines and dimensions shown in the drawing shall be within the limits given below: Table 3.2 limits of tolerances on the shapes, lines and dimensions a) Deviation from specified dimensions

12±6 mm

of cross-section of columns and beams b) Deviation from dimensions of footings 1) Dimensions in plan

50±12mm

2) Eccentricity

0.02 times the width of the footing in the direction of 74

deviation but not more than 50mm 3)Thickness

+ 0.05 times the specified thickness

These tolerances apply to concrete dimensions only, and not to positioning of vertical reinforcing steel or dowels. The number of props left under, their sizes and disposition shall be such as to be able to safely carry the full dead load of the slab, beam as the case may be together with any live load likely to occur during curing or further construction. 3.2.4.2 Cleaning and treatment of formwork All rubbish, particularly, chippings, shavings and sawdust shall be removed from the interior of the forms before the concrete is placed. The face of formwork in contact with the concrete shall be cleaned and treated with form release agent. Release agents should be applied so as to provide a thin uniform coating to the forms without coating the reinforcement. 3.2.4.3 Reinforcement Reinforcement shall be bent and fixed in accordance with procedure specified in IS 2502. The high strength deformed steel bars should not be re-bendor straightened without the approval of engineer-in charge. Bar bending schedules shall be prepared for all reinforcement work. All reinforcement shall be placed and maintained in the position shown in the drawings by providing proper cover blocks, spacers, supporting bars, etc. Crossing bars should not be tack-welded for assembly of reinforcement

unless

permitted.

Welded

joints

or

mechanical

connections in reinforcement may be used but in all cases of important connections, tests shall be made to prove that the joints are of the full strength of bars connected. Welding of reinforcements shall be done in 75

accordance with the recommendations of IS 275 1 and IS 9417. Where reinforcement bars up to 12 mm for high strength deformed steel bars and up to 16 mm for mild steel bars are bent aside at construction joints and afterwards bent back into their original positions, care should be taken to ensure that at no time is the radius of the bend less than 4 bar diameters for plain mild steel or 6 bar diameters for deformed bars. Care shall also be taken when bending back bars, to ensure that the concrete around the bar is not damaged beyond the band. Reinforcement should be placed and tied in such a way that concrete placement be possible without segregation of the mix. Reinforcement placing should allow compaction by immersion vibrator. Within the concrete mass, different types of metal in contact should be avoided to ensure that bimetal corrosion does not take place. 3.2.4.3 Concreting The concrete shall be deposited as nearly as practicable in its final position to avoid re-handling. The concrete shall be placed and compacted before initial setting of concrete commences and should not be subsequently disturbed. Methods of placing should be such as to preclude segregation. Care should be taken to avoid displacement of reinforcement or movement of formwork. As a general guidance, the maximum permissible free fall of concrete may be taken as 1.5 m. 3.2.4.4 Compacting Concrete should be thoroughly compacted and fully worked around the reinforcement, around embedded fixtures and into comers of the formwork Concrete shall be compacted using mechanical vibrators complying with IS 2505, IS 2506, IS 2514 and IS 4656. Over vibration and under vibration of concrete are harmful and should be avoided. Vibration of very wet mixes should also be avoided. Whenever vibration has to be applied externally, the design of formwork and the

76

disposition of vibrators should receive special consideration to ensure efficient compaction and to avoid surface blemishes. 3.2.4.5 Curing Curing is the process of preventing the loss of moisture from the concrete whilst maintaining a satisfactory temperature regime. The prevention of moisture loss from the concrete is particularly important if the water cement ratio is low, if the cement has a high rate of strength development, if the concrete contains granulated blast furnace slag or pulverised fuel ash. The curing regime should also prevent the development of high temperature gradients within the concrete. The rate of strength development at early ages of concrete made with super sulphated cement is significantly reduced at lower temperatures. Super sulphated cement concrete is seriously affected by inadequate curing and the surface has to be kept moist for at least seven days. 3.2.4.6 Stripping time of form work & finishing Forms shall not be released until the concrete has achieved strength of at least twice the stress to which the concrete may be subjected at the time of removal of formwork. The strength referred to shall be that of concrete using the same cement and aggregates and admixture, if any, with the same proportions and cured under conditions of temperature and moisture similar to those existing on the work. While the above criteria of strength shall be the guiding factor for removal

of

formwork,

in

normal

circumstances

where

ambient

temperature does not fall below 15°C and where ordinary Portland cement is used and adequate curing is done. Where the shape of the element is such that the formwork has reentrant angles, the formwork shall be removed as soon as possible after the concrete has set, to avoid shrinkage cracking occurring due to the restraint imposed. 77

Fig.3.30: Diaphragm wall

78

4

Chapte r RESULTS & DISCUSSIONS

Tests for Materials 4.1 Tests for Aggregates Table 4.1: Physical properties S. No.

Properties

1

Nominal Size 20 mm

10 mm

Specific Gravity

2.65

2.64

2

Impact Value

23.0 %

----

3

Abrasion Value

21.0 %

----

4

Bulk Density (Compacted)

1.64 gm/cc

1.53 gm/cc

5

Water Absorption

0.77 %

0.85 %

6

Free Surface moisture

Nil

Nil

Source: VNC Table 4.2: Gradation of Coarse Aggregates

Source: VNC 80

4.2 Tests for Fine Aggregate Fine Aggregate Gradation (Sieve Analysis) Specific Gravity

:

2.63

Bulk Density

:

1.83 gm/cc

Free Surface Moisture :

0.20 %

Gradation

:

As per table 4.3

Fineness Modulus

:

2.41

Silt Content

:

0.80 %

Table 4.3: Gradation of fine aggregate

Source : VNC

81

4.3 Tests for Reinforcement: Reinforcement is very important and essential part of any construction work there are some important tests are conducted at VNC Lab. Test result of these are given below in the table 4.4

Table 4.3: Tests on reinforcement bars of different diameter Test Required: Tensile strength, Yield stress, % Elongation, Nominal mass, Bend test, Rebend test S.No.

Name of test

1

Standard

Actual sample

specification

results

Remarks

Nominal Dia. 10mm Tensile strength

Min. 485 MPa

721.0 MPa

Yield stress

Min. 415 MPa

556.0 MPa

% Elongation

Min. 14.5 %

20.2 %

Nominal mass

0.617 kg/m

0.620 kg/m

Bend Test

There shall not be

No transverse crack

any transverse

observed

crack Rebend Test

confirm to IS:1786-1985 for Fe 415 grade with respect to test performed

There shall not be

No fracture

any fracture in

observed in bent

bent portion 2

All samples

portion

Nominal Dia. 12mm Tensile strength

Min. 485.0 MPa

612.0 MPa

Yield Stress

Min. 415.0 MPa

525.0 MPa

% Elongation

Min. 14.5 %

17.5 %

Nominal Mass

0.888 kg/m

0.908 kg/m

Bend Test

There shall be not

No transverse crack

any transverse

observed

confirm to IS:1786-1985 Grade Fe-415 in respect of test

crack Rebend Test

All Samples

There shall not be

No fracture

any fracture in

observed in bent

bent portion

portion

82

performed

3

Nominal Dia. 16mm Tensile strength

Min. 485.0 MPa

593.0 MPa

Yield Stress

Min. 415.0 MPa

524.0 MPa

% Elongation

Min. 14.5 %

25.0 %

Nominal Mass

1.580 kg/m

1.58 kg/m

Bend Test

There shall be not

No transverse crack

any transverse

observed

crack Rebend Test

All Samples confirm to IS:1786-1985 Grade Fe-415 in respect of test performed

There shall not be

No fracture

any fracture in

observed in bent

bent portion

portion

Source: VNC

83

4.4 Tests for Concrete Mix Design (M25) Target Avg. comp. strength (fck ) (IS: 10262-1982 Clause 2.2) The target average strength required to be achieved by the designed mix in the laboratory Fck = fck + t x s = 25 + 1.65 x 5.3 = 33.75 N/mm2 where, Fck = Target average compressive strength at 28 days (N/mm2) fck = Characteristic compressive strength in 28 days (N/mm2) t = Statistical factor depending upon no. of tests and acceptable low results s = Standard deviation Fck =33.75 N/mm2 Quantity of materials for the mix (IS: 10262-1982, Clause-3) Corresponding to the design strength of concrete mix the following ratio and quantities are obtained as per standard guidelines. (i)

Water Cement Ratio

:

0.465

(ii)

Water

:

169.73 L/m3

(iii)

Cement

:

365.0 kg/m3

(iv)

Sand Content

:

580.35 kg/m3

(v)

Coarse Agg(10 mm)

:

627.80 kg/m3

:

627.80 kg/m3

:

82.0 mm

(vii) Filling Frequency

:

3 Cubes on (5m3-10m3)

(viii) Curing

:

7 – 28 days

(20 mm) (vi)

Slump

84

Fig. 4.1: Cube curing by ponding 4.4.1 Compressive Strength Test Following table shows the test results of concrete cube after 28 days. Table 4.6: Compressive strength test results

Source: VNC

85

Fig. 4.2: Compressive strength testing machine 4.4.2 Slump Test Following table shows the slump test result Table 4.7: Result of slump test

Source: VNC

86

Different Grades of Concrete These various kind of concrete grades were used for concrete work at site. Following shows the properties and these mix gradients. Table 4.8: Constituents of different grades of concrete S.No.

Water

w/c 3

(kg/m )

Ratio

M-45

179.10

M-40 M35

Aggregate

Sand

Cement 3

Slump

Admixture

(kg/m )

(mm)

414.0

488

105

1%

632.15

465.3

470

105

1%

571.16

571.16

601.6

436

70

1%

0.405 %

565.76

565.76

596.7

442

130

172.00

0.430 %

730.00

487.00

450.0

400

90

M-25

169.73

0.465 %

627.80

627.80

580.3

365

82

M-20

189.70

0.542 %

579.25

579.25

630.0

350

44

M-15

169.88

0.548 %

627.75

627.75

626.2

310

66

20 mm

10 mm

0.367 %

732.00

599.00

174.84

0.367 %

632.15

174.40

0.400 %

179.01

M-30

(Cap) M35 (Pile)

Source: VNC

87

Chapte r

5

CONSTRUCTION MANAGMENT

Construction Planning 5.1 Basic Concepts in the Development of Construction Plan Construction planning is a fundamental and challenging activity in the management and execution of construction projects. It involves the choice of technology, the definition of work tasks, the estimation of the required resources and durations for individual tasks, and the identification of any interactions among the different work tasks. A good construction plan is the basis for developing the budget and the schedule for work. Developing the construction plan is a critical task in the management of construction, even if the plan is not written or otherwise formally recorded. In addition to these technical aspects of construction planning, it may also be necessary to make organizational decisions about the relationships between project participants and even which organizations to include in a project. For example, the extent to which sub-contractors will be used on a project is often determined during construction planning. In developing a construction plan, it is common to adopt a primary emphasis on either cost control or on schedule control as illustrated in Fig. 5.1. Some projects are primarily divided into expense categories with associated costs. In these cases, construction planning is cost or expense oriented. Within the categories of expenditure, a distinction is

89

made between costs incurred directly in the performance of an activity and indirectly for the accomplishment of the project. Scheduling of work activities over time is critical and is emphasized in the planning process. In this case, the planner insures that the proper precedence’s among activities are maintained and that efficient scheduling of the available resources prevails.

Fig. 5.1 Alternative emphases in construction planning 5.2 Choice of Technology and Construction Method In selecting among alternative methods and technologies, it may be necessary to formulate a number of construction plans based on alternative methods or assumptions. Once the full plan is available, then

the

cost,

time

and

reliability

impacts

of

the

alternative

approaches can be reviewed. This examination of several alternatives is often made explicit in bidding competitions in which several

90

alternative designs may be proposed or value engineering for alternative construction methods may be permitted 5.3 Work Tasks The definition of appropriate work tasks can be a laborious and tedious process, yet it represents the necessary information for application of formal scheduling procedures. Since construction projects can involve thousands of individual work tasks, this definition phase can also be expensive and time consuming. Fortunately, many tasks may be repeated in different parts of the facility or past facility, construction plans can be used as general models for new projects. 5.4 Defining Precedence Relationships among Activities Once work activities have been defined, the relationships among the activities can be specified. Precedence relations between activities signify that the activities must take place in a particular sequence. Numerous natural sequences exist for construction activities due to requirements for structural integrity, regulations, and other technical requirements. For example, design drawings cannot be checked before they are drawn. Diagrammatically, precedence relationships can be illustrated by a network or

graph in which the activities are

represented by arrows as in (Fig. 5.2). The arrows in Fig.5.2 are called branches or links in the activity network, while the circles marking the beginning or end of each arrow are called nodes or events. In this figure, links represent particular activities, while the nodes represent milestone events.

Fig. 5.2 Illustrative Set of Four Activities with Precedences 91

More complicated precedence relationships can also be specified. For ex ample, one activity might not be able to start for several days after the completion of another activity. As a common example, concrete might have to cure (or set) for several days before formwork is removed. This restriction on the removal of forms activity is called a lag between the completion of one activity (i.e., pouring concrete in this case) and the start of another activity (i.e., removing formwork in this case). Many computers based scheduling programs permit the use of a variety of precedence relationships. 5.5 Estimating Activity Durations In most scheduling procedures, each work activity has associated time duration. These durations are used extensively in preparing a schedule. For example, suppose that the durations shown in Table 5.1. The entire set of activities would then require at least 8 days, since the activities follow one another directly and require a total of 2.0 + 2 + 3+ 1.0 = 8 days. If another activity proceeded in parallel with this sequence, the 8 day minimum duration of these four activities is unaffected. More than 8 days would be required for the sequence if there was a delay or a lag between the completion of one activity and the start of another. Table 5.1 Durations and Predecessors for a Four Activity Project Illustration Activity

Predecessor

Duration (Days)

Excavate trench

---

2

Place formwork

Excavate trench

2

Place reinforcing

Place formwork

3

Pour concrete

Place reinforcing

1

92

A probability distribution indicates the chance that particular activity duration will occur. In advance of actually doing a particular task, we cannot be certain exactly how long the task will require. 5.6 Estimating Resource Requirements for Work Activities In addition to precedence relationships and time durations, resource requirements are usually estimated for each activity. Since the work activities defined for a project are comprehensive, the total resources required for the project are the sum of the resources required for the various activities. By making resource requirement estimates for each activity, the requirements for particular resources during the course of the project can be identified. Potential bottlenecks can thus be identified, and schedule, resource allocation or technology changes made to avoid problems. The initial problem in estimating resource requirements is to decide the extent and number of resources that might be defined. At a very aggregate level, resources categories might be limited to the amount of labor (measured in man-hours or in do), the amount of materials required for an activity, and the total cost of the activity. At this aggregate level, the resource estimates may be useful for purposes of project monitoring and cash flow planning. 5.7 Reporting Day to day work should be reported with accuracy in measurement in prescribed format 5.8 Safety As with all the other costs of construction, it is a mistake for owners to ignore a significant category of costs such as injury and illnesses. While contractors may pay insurance premiums directly, these costs 93

are reflected in bid prices or contract amounts. Delays caused by injuries and illnesses can present significant opportunity costs to owners. In the long run, the owners of constructed facilities must pay all the costs of construction. During the construction process itself, the most important safety related measures are to insure vigilance and cooperation on the part of managers, inspectors and workers. Vigilance involves considering the risks of different working practices. In also involves maintaining temporary physical safeguards such as barricades, braces, guy lines, railings, toe boards and the like. Sets of standard practices are also important, such as: 

Requiring hard hats on site.



Requiring eye protection on site.



Requiring hearing protection near loud equipment.



Insuring safety shoes for workers.



Providing first-aid supplies and trained personnel on site

While eliminating accidents and work related illnesses is a worthwhile goal, it will never be attained. Despite these peculiarities and as a result of exactly these special problems, improving worksite safety is a very important project management concern.

94

5. 9 Rec om me nd at io ns  Co ns tr uc ti on of an y wo rk sh ou ld st ar t on ly af te r ta ki ng al l me as ur es of sa fe ty li ke pr op er li gh ti ng ar ra ng em en t, re fl ec ti ve sa fe ty ta pe s et c.  Tr af fi c

pl an ni ng

fo r

GO

&

FR O

Ve hi cl es

sh ou ld

be

di ve rt ed , el im in at in g Tr af fi c ja ms .  Pl an ni ng

of

su ch

pr oj ec ts

sh ou ld

be

co mp le te ly

su pp or te d by a fi rm po li ti ca l wi ll in vo lv in g al l us er s an d af fe ct ed ag en ci es or pe rs on s.  Al l sa fe ty

me as ur es

as

pe r

sa fe ty

co de s

sh ou ld

be

en su re d by ex ec ut in g as we ll as su pe rv is in g ag en ci es to av oi d lo ss of li fe an d pr op er ty .  Al l ma nd at or y te st s sh ou ld be co nd uc te d an d pr oper re co rd s ma in ta in ed fo r th e fu ll li fe of su ch pr oj ec ts . Te st s fr om ou ts id e ag en ci es sh al l on ly be go t do ne fr om ac cr ed it ed la bs on ly .  Wh en su ch pr oj ec ts ar e ta ke n in ur ba n ar ea s co mp le te de ta il s

of

un de rg ro un d

wa te r,

el ec tr ic ,

se wa ge ,

te le ph on e li ne s mu st be ob ta in ed to av oi d tr af fi c ja ms an d in co nv en ie nc e to pu bl ic .  No co mp ro mi se sh ou ld be ma de wi th Qu al it y Co nt ro l no rm s la id pr op er ty

do wn

an d

in

li fe .

va ri ou s co de s to Th er e

sh ou ld

be

avo id a

lo ss

of

co mp le te

co or di na ti on be tw ee n de si gn er s an d ex ec ut or s. Pu tt in g up

bl am es

on

ea ch

ot he r

is

a

en gi ne er in g co mm un it y as a wh ol e.

95

ma jo r

lo ss

to

th e

Appendix I (Illustrative example on concrete Mix Design) An example illustrating the mix design for a concrete of M 20 grade is given below: DESIGN STIPULATIONS Grade Designation

=

M40

Type of cement

=

O.P.C 43 grade

Brand of cement

=

XXX

Admixture

=

XXX

Fine Aggregate

=

Zone-II

Sp. Gravity Cement

=

3.15

Fine Aggregate

=

2.61

Coarse Aggregate (20mm)

=

2.65

Coarse Aggregate (10mm)

=

2.66

Minimum Cement (As per contract)

=

400 kg /m 3

Maximum water cement ratio (As per contract) =

0.45

Mix Calculation: 1. Target Mean Strength = 40 + (5 x1.65) = 48.25 MPa 2. Selection of water cement ratio Assume water cement ratio = 0.4 3. Calculation of cement content: Assume cement content 400 kg /m

3

(As per contract Minimum cement content 400 kg /m 3)

97

4. Calculation of water 400 X 0.4 = 160 kg Which is less than 186 kg (As per Table No. 4, IS: 10262) Hence o.k. 5. Calculation for C.A. & F.A.: – As per IS: 10262, Cl. No. 3.5.1 V = [W + (C/Sc ) + (1/p)x(fa/Sfa ) ] x (1/1000) V = [W + (C/Sc ) + {1/(1-p)}x(ca/Sca) ] x (1/1000) Where V = absolute volume of fresh concrete, which is equal to gross volume 3

(m ) minus the volume of entrapped air, W = mass of water (kg) per m 3 of concrete, C = mass of cement (kg) per m3 of concrete, Sc = specific gravity of cement, (p) = Ratio of fine aggregate to total aggregate by absolute volume , (fa) , (ca) = total mass of fine aggregate and coarse aggregate (kg) per 3

m of Concrete respectively, and Sfa, Sca = specific gravities of saturated surface dry fine aggregate and Coarse aggregate respectively. (As per Table No. 3, IS-10262), for 20mm maximum size entrapped air is 2% . Assume F.A. by % of volume of total aggregate = 36.5 % 0.98 = [160 + (400 / 3.15) + (1 / 0.365) (Fa / 2.61)] (1 /1000)

98

Fa = 660.2 kg ≈ 660 kg. 0.98 = [160 + (400 / 3.15) + (1 / 0.635) (Ca / 2.655)] (1 /1000) Ca = 1168.37 kg ≈ 1168 kg. Considering 20 mm: 10mm =

0.6: 0.4

20mm

=

701 kg

10mm

=

467 kg

Cement

=

400 kg

Water

=

160 kg

Fine aggregate

=

660 kg

Coarse aggregate 20 mm

=

701 kg

Coarse aggregate 10 mm

=

467 kg

Admixture

=

0.6 % by weight of cement = 2.4 kg

Recron 3S

=

900 gm

Hence Mix details per m 3

Water: cement: F.A.: C.A. =

0.4: 1: 1.65: 2.92

Observation A. Mix was cohesive and homogeneous. B. Slump

=

110mm

C. No. of cube casted

=

12 Nos.

7 days average compressive strength

=

51.26 MPa.

28 days average compressive strength

=

62.96 MPa which is

greater than 48.25MPa Hence the mix is accepted.

99

Appendix II Bar bending Schedule of diaphragm wall as per drawing

100

101

102

103

104

Appendix III Level Transferred to Pier for Casting of Pier cap To mark the bottom level of pier cap on the pier the bottom level of pier cap should be known that will attained by reducing the thickness of wearing course ,deck slab, diaphragm wall and thickness of pier cap.

All dimensions are in m

105

198.695 - 195.00

pier cap bottom level (as per drawing) zero level

3.695 + 1.500 5.195 - 0.300 4.895

height of zero level form ground level height of pier cap bottom from ground level adjustable margin scaffolding had to be provided up to this height from G.L

Thus scaffolding is to be provided leaving a margin space of 300mm for ISMB125,

0.125 m

adjustable jack

0.170 m

shutter plate

0.005 m 0.300 m

106

Appendix IV

Calculation for leveling bearing The level of bearing were fixed as per drawings, the top level of pier cap was known by drawing and calculations so firstly set a auto level ,level and center it take back sight as the top level of the pier cap determine the height of instrument.

All dimensions are in m

107

Suppose H.I of the instrument is 1.48 203.14 + 1.48

=

204.62

-203.14 + 0.45

=

203.59 1.03m

Now place the staff on the top surface of bearing ,the actual reading appear on staff is to be 1.03m,else shift the top of bearing up or down as if actual reading on staff is greater than theoretical reading then shift the top of bearing downward or vice versa until the actual reading and theoretical reading do not concede. Repeat same procedure for levellling of stool for girder.

108

References List of IS codes Referred  IS 456 -2000 Plain & Reinforced concrete code of practice  IS 383-1993

Specification for Coarse and Fine Aggregate from

natural  sources for concrete  IS: 383 Zone-III- specifications for Coarse & Fine Agg. From natural sources for Concrete.

 IS 1786 -1985 Specification for High strength Deformed steel bars and wires for Concrete Reinforcement  IS 2386 (Part - II) 1991 Method for Test for aggregates for concrete Part - II Estimation of deleterious materials and organic impurities  SP-34 Hand Book on concrete reinforcement and Detailing  SP-23 Hand Book on concrete Mix.  IS 9103 1979 Specification for admixtures for concrete  IS-383-1970.The grading of coarse aggregates should be as per specifications

109

 IS 2751 and IS 9417 Welding of reinforcements in accordance with the recommendations  IS: 1786 1985 Test to be performed in Respect of Fe 415  IS: 10262 1982 Recommended Guidelines for Concrete Mix Design.  IS: 516 1959 Methods of tests for Strength of Concrete.

Books  General Theory of Bridge Construction by Hermann Haupt  Design and construction of bridge approaches by Harvey E. Wahls  Bridge engineering: construction and maintenance by Wai-Fah Chen  Design Of R.C.C. Structural Elements by S.S. Bhavikatti  Significance of tests and properties of concrete by Joseph F. Lamond, J. H. Pielert  Materials in construction: an introduction by Geoffrey D. Taylor  Advances in Construction Materials 2007 by Christian U. Grosse  Reinforced concrete: a fundamental approach by Edward G. Nawy

110

 Corrugated

plastic

ducts

for

internal

bonded

post-tensioning

Fédération internationale du béton  Post-tensioning manual by Post-Tensioning Institute  Practical handbook of grouting: soil, rock, and structures by James Warner  Aggregates: sand, gravel and crushed rock aggregates for By Mick R.Smith,  Aggregates in concrete by Mark G. Alexander, Sidney Mindess  Manual of ready-mixed concrete by J. D. Dewar, R. Anderson  Construction management: new directions by W. D. McGeorge, Angela Palmer, Kerry London  Formwork for concrete by Mary Krumboltz Hurd

 Bridge bearings and expansion joints by David John Lee

 Structural bearings - Page 62 byHelmut Eggert, Wolfgang Kauschke

 E- sources

111

Suggestions

112

Suggestions

113

Conclusion The primary objective of this report is a description of practical knowledge. I attained on construction site of an interchange structure during my summer internship training. In the period of training, i closely studied the aspects of

practical application of various methodologies and learnt the art of being pioneer in solving practical problem faced at site; during the course of my study i attained the following conclusions:  There are differences between theoretical and practical approach to execute various construction process. Theoretical knowledge is insufficient to commence task at site.  The quality of construction work was at priority with respect to time. Various check were formatted at each step of construction to ensure the quality of work.  After the consecutive revisions of drawing, they are finally revised to fulfil the requirements of site.  The various factors such as climatic conditions, man power, availability of resources and methods involved in construction plays a crucial role in an optimised completion of project.  Safety measures were taken to avoid injuries and accidents on site.

This report elaborates the sequence of work for construction of structural components in a bridge. The report contains the characteristics of materials and technique used in construction of RCC bridge. It gives a brief introduction to construction planning.

96