High Strength Concrete (M70)

Dr B R Ambedkar National Institute of Technology

HIGH STRENGTH (M70) AND HIGH PERFORMANCE CONCRETE

Batch 2009-2013

Final Year Project Report.

Project Team Members Anik Yadav

09103009

Shayon Ghosh Sanjeev Shah

09102072 09102066

Ashish Vijay

09102019

High strength (M70) and High Performance Concrete

Acknowledgement We take immense pleasure in thanking Professor Dr S .P Singh, Head Department of Civil Engineering NITJ who had been a source of inspiration

and for his timely guidance in the conduct of our Project. We would also like to thank Faculty Members of Department of Civil Engineering NIT Jalandhar for their guidance and for providing required resources to complete our Project successfully.

We wish to express our deep sense of gratitude to Non-teaching Faculty of Department of Civil Engineering NIJ for facilitating us and helping us to completing the project work, successfully.

Page 1

High strength (M70) and High Performance Concrete

Content Page Introduction

3-4

Properties of High performance Concrete

4-7

Methods for achieving High Performance

7-8

High-performance Concrete Parameters.

8-9

Material Selection

9-16

Mix Proportion

16-18

Objective

18-19

Mix Design of M70

19-23

Laboratory tests

24-26

Preparation of Mix Test Results

26-31 31-33

Graphs

33-36

Conclusion

37

Page

2

High strength (M70) and High Performance Concrete

High strength (M70) and High Performance Concrete CONCRETE IS DEFINED SOLELY ON THE BASIS OF MEASURED AT A GIVEN AGE.

- STRENGTH CONCRETE” ITS COMPRESSIVE STRENGTH

AS “HIGH

High performance concrete (HPC) for concrete mixtures possessing high workability, high

durability and high ultimate strength. Concrete, whose ingredients, proportions and production methods are specifically chosen to meet special performance and uniformity requirements that cannot be always achieved routinely by using only conventional materials, like, cement, aggregates, water and chemical admixtures, and adopting normal mixing, placing and curing practices. These performance requirements can be high strength, high early strength, high workability, low permeability and high durability for severe service environments, etc. or combinations thereof. Production and use of such concrete in the field necessitates high degree of uniformity between batches and very stringent quality control.

High performance concrete (HPC) is a specialized series of concrete designed to provide several benefits in the construction of concrete structures that cannot always be achieved routinely using conventional ingredients, normal mixing and curing practices. In the other words a high performance concrete is a concrete in which certain characteristics are developed for a particular application and environment, so that it will give excellent performance in the structure in which it will be placed, in the environment to which it will be exposed, and with the loads to which it will be subjected during its design life. It includes concrete that provides either substantially improved resistance to environmental influences (durability

in

service)

or

substantially

increased

structural

capacity

while maintaining adequate durability. It may also include concrete, which significantly reduces construction time without compromising long-term serviceability. While high strength concrete, aims at enhancing strength and consequent advantages owing to improved

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High strength (M70) and High Performance Concrete

strength, the term high-performance concrete (HPC) is used to refer to concrete of required performance for the majority of construction applications without compromising long-term serviceability. While high strength concrete, aims at enhancing strength and consequent advantages owing to improved strength, the term high-performance concrete (HPC) is used to refer to concrete of required performance for the majority of construction applications.

Properties of High performance Conc rete •

High modulus of elasticity

•

High abrasion resistance

•

High durability and long life in severe environments

•

Low permeability and diffusion

•

Resistance to chemical attack

•

High resistance to frost and deicer scaling damage

•

Toughness and impact resistance • Ease of placement •

Chemical Attack

•

Carbonation

High Modulus of elasticity The modulus of elasticity is a very important mechanical property of concrete. The higher the value of the modulus, the stiffer the material is. Thus, comparing a high performance concrete to a normal strength concrete, it is seen that the elastic modulus for high performance concrete will be higher, thereby making it a stiffer type of concrete. Stiffness

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High strength (M70) and High Performance Concrete

is a desirable property for concrete to have because the deflection a structure may experience will be decreased. However, deformations, such as creep, increase in high strength concrete

High abrasion resistance Abrasion resistance is directly related to the strength of concrete. This makes high strength HPC ideal for abrasive environments. The abrasion resistance of HPC incorporating silica fume is especially high. This makes silica fume concrete particularly useful for spillways and stilling basins, and concrete pavements or concrete pavement overlays subjected to heavy or abrasive traffic.

High durability and long life in severe environments. Durability problems of ordinary concrete can be associated with the severity of the environment and the use of inappropriate high water/binder ratios. High-performance concrete that have a water/binder ratio between 0.30 and 0.40 are usually more durable than ordinary concrete not only because they are less porous, but also because their capillary and pore networks are somewhat disconnected due to the development of selfdesiccation. In high-performance concrete (HPC), the penetration of aggressive agents is quite difficult and only superficial

Low permeability and diffusion The durability and service life of concrete exposed to weather is related to the permeability of the cover concrete protecting the reinforcement. HPC typically has very low permeability to air, water, and chloride ions. Low permeability is often specified through the use of a coulomb value, such as a maximum of 1000 coulombs. The dense pore structure of high-performance concrete, which makes it so impermeable, gives it characteristics that make it eminently suitable for uses where a high quality concrete would not normally be considered

Resistance to chemical attack Page 5

High strength (M70) and High Performance Concrete

For resistance to chemical attack on most structures, HPC offers a much improved performance. Resistance to various sulfates is achieved primarily by the use of a dense, strong concrete of very low permeability and low water-to-cementing materials ratio; these are all characteristics of HPC. Similarly resistance to acid from wastes is also much improved.

High resistance to frost and deicer scaling damage Because of its very low water-cementing materials ratio (less than 0.30), it is widely believed that HPC should be highly resistant to both scaling and physical breakup due to freezing and thawing. There is ample evidence that properly air-entrained high performance concretes are highly resistant to freezing and thawing and to scaling

Toughness and impact resistance Both normal-strength concrete and high-strength concrete are brittle, with the degree of brittleness increasing with increasing strength. The dynamic mechanical performance of highstrength concrete (HSC) under impact or fatigue loading has received increasing attention in recent years because of the rapid adoption of higher strength concrete in bridges, pavements, and marine structures, and several researchers have studied the impact or fatigue performance of concrete. Many experimental results have indicated that the characteristics and microstructure of both the interfacial zone and the bulk HSC are improved by incorporating silica fume. As well, the addition of steel fibers can effectively restrain the initiation and propagation of crack under stress, and improve the toughness. Ease of Placement

High performance concrete can also be highly workable self-compacting concrete which is type of HPC which can be easily placed even dense reinforcement where vibrators can’t

be used.

Chemical Attack For resistance to chemical attack on most structures, HPC offers a much improved performance. Resistance to various sulfates is achieved primarily by the use of a dense, Page

6

High strength (M70) and High Performance Concrete

strong concrete of very low permeability and low water-to-cementing materials ratio; these are all characteristics of HPC. Similarly resistance to acid from wastes is also much improved

Carbonation HPC has a very good resistance to carbonation due to its low permeability. It was determined that after 17 years the concrete in the CN Tower in Toronto had carbonated to an average depth of 6 mm (0.24 in.). The concrete mixture in the CN Tower had a water-cement ratio of 0.42. For a cover to the reinforcement of 35 mm (1.4 in.), this concrete would provide corrosion protection for 500 years. For the lower water cementing materials ratios common to HPC, significantly longer times to corrosion would result, assuming a crack free structure. In practical terms, uncracked HPC cover concrete is immune to carbonation to a depth that would

Methods for achieving High Performance In general, better durability performance has been achieved by using high-strength, low W/c ratio concrete. Though in this approach the design is based on strength and the result is better durability, it is desirable that the high performance, namely, the durability, is addressed directly by optimizing critical parameters such as the practical size of the required materials. Two approaches to achieve durability through different techniques are as follows. 1. Reducing the capillary pore system such that no fluid movement can occur is the first approach. This is very difficult to realize and all concrete will have some interconnected pores.

2. Creating chemically active binding sites which prevent transport of aggressive ions such as chlorides is the second more effective method.

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High strength (M70) and High Performance Concrete

High-performance Concrete Parameters. Permeation is a major factor that causes premature deterioration of concrete structures. The provision of high-performance concrete must center on minimizing permeation through proportioning methods and suitable construction procedures (curing) to ensure that the exposure conditions do not cause ingress of moisture and other agents responsible for deterioration. It is important to identify the dominant transport phenomenon and design the mix proportion with the aim of reducing that transport mechanism which is dominant to a predefined acceptable performance limit based on permeability.

9The parameter to be controlled for achieving the required performance criteria could be any of the following. (1) Water/ (cement + mineral admixture) ratio (2) Strength (3) Densification of cement paste (4) Elimination of bleeding (5) Homogeneity of the mix (6) Particle size distribution (7) Dispersion of cement in the fresh mix (8) Stronger transition zone (9) Low free lime content (10) Very little free water in hardened concrete

Page

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High strength (M70) and High Performance Concrete

Material Selection The main ingredients of HPC are almost the same as that of conventional concrete. These are 1) Cement 2) Fine aggregate 3) Coarse aggregate 4) Water 5) Mineral admixtures (fine filler and/or pozzolanic supplementary cementation materials) 6) Chemical admixtures (plasticizers, superplastisizers, retarders, air-entraining agents)

Cement There are two important requirements for any cement: (a) strength development with time and (b) facilitating appropriate rheological characteristics when fresh. 1) High C3A content in cement generally leads to a rapid loss of flow in fresh concrete. Therefore, high C3A content should be avoided in cements used for HPC. 2) The total amount of soluble sulphate present in cement is a fundamental consideration for

the suitability of cement for HPC. 3) The fineness of cement is the critical parameter. Increasing fineness increases early

strength development, but may lead to rheological deficiency. 4) The super plasticizer used in HPC should have long molecular chain in which the sulphonate

group occupies the beta position in the poly condensate of formaldehyde and melamine sulphonate or that of naphthalene sulphonate.

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High strength (M70) and High Performance Concrete

5) The compatibility of cement with retarders, if used, is an important requirement.

Coarse aggregates The important parameters of coarse aggregate that influence the performance of concrete are its shape, texture and the maximum size. Since the aggregate is generally stronger than the paste, its strength is not a major factor for normal strength concrete, or for HES and VES concretes. However, the aggregate strength becomes important in the case of high performance concrete. Surface texture and mineralogy affect the bond between the aggregates and the paste as well as the stress level at which micro cracking begins. The surface texture, therefore, may also affect the modulus of elasticity, the shape of the stressstrain curve and to a lesser degree, the compressive strength of concrete. Since bond strength increases at a slower rate than compressive strength, these effects will be more pronounced in HES and VES concretes. Tensile strengths may be very sensitive to differences in aggregate surface texture and surface area per unit volume.

Fine aggregate Fine aggregates (FA) with a rounded particle shape and smooth texture have been found to require less mixing water in concrete and for this reason are preferable in HSC. HSC typically contain such high contents of fine cementations materials that the grading of the FA used is relatively unimportant. However, it is sometimes helpful to increase the fineness modulus (FM) as the lower FM of FA can give the concrete a sticky consistency (i.e. making concrete difficult to compact) and less workable fresh concrete with a greater water demand. Therefore, sand with a FM of about 3.0 is usually preferred for HSC (ACI 363R, 1992).

Compressive strength of coarse aggregate To make high-strength concrete we must obviously use coarse aggregate that has a high compressive strength prevent rupture fromfrom occurring in the coarse aggregate. We must therefore find coarse to aggregates that come quarries that produce rocks with compressive strengths above 16,500 psi7 and absolutely avoid rocks that are too soft or which present cleavage planes. So before making laboratory trial batches, we should

Page

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High strength (M70) and High Performance Concrete

determine the compressive strengths of all the coarse aggregates economically available. Yet, as already noted, it is not necessarily the strongest coarse aggregate which will produce the strongest concrete, since the bond of the hydrated cement to that same aggregate must be taken into account.

Shape of coarse aggregate Because the bond between the coarse aggregate and the hydrated cement is more of a mechanical type at the beginning, to make high-strength concrete we ought to use a cubically shaped crushed stone rather than a natural gravel or a crushed gravel. The type of crusher used by the aggregate producer is important in this respect. Furthermore, the surfaces of the coarse aggregate must be clean and free of any dust which would impair mechanical bonding. In certain cases, washing of the aggregate may prove necessary. Careful examination of aggregate samples from local quarries is sufficient to choose the coarse aggregate that offers the most useful characteristics from this point of view.

Maximum size of coarse aggregate We could show that for a given aggregate there is a relation between its maximum diameter and the maximum compressive strength possible from concrete made with it. The absolute maximum strength seems to be obtained with aggregates having a maximum size of 3 ⁄8 or 1⁄2 inch.8 Standard coarse aggregates of Number 4 to- 3 ⁄8-inch 9 or Number 4-to-5⁄8-inch10 sizes are the most suitable.

Effect of Aggregate Type The intrinsic strength of coarse aggregate is not an important factor if water-cement ratio falls within the range of 0.50 to 0.70, primarily due to the fact that the cement-aggregate bond or the hydrated cement paste fails long before aggregates do.It is, however, not true for very high strength concretes with very low water-cement ratio of 0.20 to 0.30. For such concretes, aggregates can assume the weaker-link role and fail in the form of trans granular fractures on the failure surface. However, the aggregate minerals must be strong, unaltered, and fine grained in order to be suitable for very high strength concrete. Intraand inter-granular fissures partially decomposed coarse-grained minerals, and the presence of cleavages and lamination planes tend to weaken the aggregate, and therefore the ultimate strength of the concrete. Page 11

High strength (M70) and High Performance Concrete

The compressive strength and elastic modulus of concrete are significantly influenced by the mineralogical characteristics of the aggregates. Crushed aggregates from fine-grained debris and limestone give the best results. Concretes made from smooth river gravel and from crushed granite containing inclusions of a soft mineral are relatively weaker in strength. There exists a good correlation between the compressive strength of coarse aggregate and its soundness expressed in terms of weight loss. There exists a close correlation between the mean compressive strengths of the aggregate and the compressive strength of the concrete, ranging from 35 to 75 MPa, at both 7 days and 28 days of age.

Effect of Aggregate Size

The use of larger maximum nominal size of aggregate affects the strength in several ways. First, since larger aggregates have less specific surface area and the aggregate-paste bond strength is less, the compressive strength of concrete is reduced. Secondly, for a given volume of concrete, using larger aggregate results in a smaller volume of paste thereby providing more restraint to volume changes of the paste. This may induce additional stresses in the paste, resulting in micro cracks prior to application of load, which may be a critical factor in very high strength (VHS) concretes. Therefore, it is the general consensus that smaller size aggregate should be used to produce high performance concrete . It is generally suggested that 10 to 12 mm is the appropriate maximum size of aggregates for making high strength concrete. However, adequate performance and economy can also be achieved with 20 to 25 mm maximum size graded aggregates by proper proportioning with a mid-range or high-range water reducer, high volume blended cements, and coarse ground Portland cement. Change in emphasis from water-cementations material ratio versus strength relation to water-content versus durability relation will provide the incentive for much closer control of aggregate grading than in the current practices. A substantial reduction in water requirement can be achieved by using a well-graded aggregate. Page

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High strength (M70) and High Performance Concrete

Mineral admixtures Mineral admixtures form an essential part of the high-performance concrete mix. These are used for various purposes, depending upon their properties. More than the chemical composition, mineralogical and granulometric characteristics determine the influence of mineral admixture's role in enhancing properties of concrete. The fly ash (FA), the ground granulated blast furnace slag (GGBS) and the silica fume (SF) has been used widely as supplementary cementations materials in high performance concrete. These mineral admixtures, typically fly ash and silica fume (also called condensed silica or micro silica), reduce the permeability of concrete to carbon dioxide (CO2) and chloride-ion penetration without much change in the total porosity. These pozzolanas react with OPC in two ways-by altering hydration process through alkali activated reaction kinetics of a pozzolanas called pozzolanic reaction and by micro filler effect. In pozzolanic reaction the pozzolanas react with calcium hydroxide, Ca(OH)2, (free lime) liberated during hydration of cement, which comprises up to 25 per cent of the hydration product, and the water to fill voids with more calcium-silicate-hydrate (nonevaporable water) that binds the aggregate particles together.

The pozzolanas may also react with other alkalis such as sodium and potassium hydroxides present in the cement paste. These reactions reduce permeability, decrease the amounts of otherwise harmful free lime and other alkalis in the paste, decrease free water content, thus increase the strength and improve the durability.

Fly ash used as a partial replacement for cement in concrete, provides very good performance. Concrete is durable with continued increase in compressive strength beyond 28 days. There is little evidence of carbonation, it has low to average permeability and

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High strength (M70) and High Performance Concrete

good resistance to chloride-ion penetration. Chloride-ion penetration rating of high volume fly ash (HVFA) concrete is less than 2000 coulombs, which indicate a very low permeability concrete. It continues to improve because many fly ash particles react very slowly, pushing the coulomb value lower and lower. Silica fume not only provides an extremely rapid pozzolanic reaction, but its very fine size also provides a beneficial contribution to concrete. Silica fume tends to improve both mechanical properties and durability. Silica fume concretes continue to gain strength under a variety of curing conditions, including unfavorable ones. Thus the concretes with silica fume appear to be more robust to early drying than similar concretes that do not contain silica fume. Silica fume is normally used in combination with high-range water reducers and increase achievable strength levels dramatically. Since no interaction between silica fume, ground granulated blast-furnace slag and fly ash occurs, and each component manifests its own cementations properties as hydration proceeds, higher strength and better flow ability can be achieved by adding a combination of SF, FA and GGBFS to OPC which provides, a system with wider particlesize distribution. HVFA concrete incorporating SF exceeds performance of concrete with only FA. The key to developing OPC-FA-SF and OPC-GBSF-SF concretes without reduction in strength is to incorporate within the mixture adequate amounts of OPC and water. Using both silica fume and fly ash, the strength at 12 hours has been found to improve suddenly over similar mixes with silica fume alone. This phenomenon has been attributed to the liberation of soluble alkalis from the surface of the fly ash.

Admixtures High Range Water Reducing Admixtures (HRWA) :These are the second generation admixture and also called as Super plasticizers. These are synthetic chemical products

Page

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High strength (M70) and High Performance Concrete

made from organic sulphonate of type RSO3, where R is complex organic group of higher molecular weight produced under carefully controlled condition: The commonly used super plasticizer are as follows: i) Sulphonate melamine formaldehyde condensate (S M F C) ii) Sulphonated napthalene formaldehyde condensate (S N F C) iii) Modified ligno-sulphonates and other sulphonic esters, acids etc. iv) Polycarboxylate Ether Polymer (PCE) Reduction in W/c Ratio is as follows against the different wa ter reducers admixtures:

1. Water Reducer Admixture: 5-12% Reduction of water. 2. Melamine/Naphthalene based admixtures: It reduces water 16-25 %. 3. Polycarboxylate ether polymer based admixture: It reduces water 20 to 35%. The main objectives for using super plasticizers are the following.

(i) To produce highly dense concrete to ensure very low permeability with adequate

resistance to freezing-hawing. (ii) To minimize the effect of heat of hydration by lowering the cement content.

(iii) To produce concrete with low air content and high workability to ensure high bond strength. (iv) To lower the water-cement ratio in order to keep the effect of creep and shrinkage to a minimum. (v) To produce concrete of lowest possible porosity to protect it against external attacks. (vi) To keep alkali content low enough for protection against alkali-aggregate reaction and to keep sulphate and chloride contents as low as possible for prevention of reinforcement corrosion. (vii) To produce pump able yet non-segregating type concrete. Page 15

High strength (M70) and High Performance Concrete

(viii) To overcome the problems of reduced workability in fiber reinforce concrete and shotcrete. (ix) To provide high degree of workability to the concretes having mineral additives with very low water-cementations material ratios. (x) To produce highly ductile and acid resistant polymer (acrylic latex) concrete with adequate workability and strength.

The following types of superplastisizers are used . • Naphthalene-based • Melamine-based • Ligno-sulphonates-based • Polycarboxylate-based • Combinations of above

Mix Proportion

The main difference between mix designs of HPC and CC is the emphasis laid on performance aspect also (in fresh as well as hardened stages of concrete) besides strength, in case of HPC, whereas in design of CC mixes, strength of concrete is an important criterion. By imposing the limitations on maximum water–cement ratio, minimum cement content, workability (slum, flow table, compaction factor, and Vee-Bee consistency), etc., it is sought to assure performance of CC; rarely any specific tests are conducted to measure the durability aspects of CC, during the mix design. In HPC, however, besides strength, durability considerations are given utmost importance. To achieve high durability of HPC, the mix design of HPC should be based on the following considerations: i) The water-binder (w/b) ratio should be as less as possible, preferably 0.3 and below.

Page

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High strength (M70) and High Performance Concrete

ii) The workability of concrete mix should be enough to obtain good compaction (use

suitable chemical admixtures such as super plasticizer (SP)). iii) The transition zone between aggregate and cement paste should be strengthened

(add fine fillers such as silica fume (SF)). iv) The microstructure of cement concrete should be made dense and impermeable (add

pozzolanic materials such as fly ash (FA), ground granulated blast furnace slag powder (GGBFSP), SF, etc.) v) Proper curing regime of concrete should be established (this is to overcome the

problems associated with usual adoption of very low water content and high cement content in HPC mixes. TYPICAL HPC MIX DESIGN METHODS

The properties of HPCs not only depend upon the w/b ratio but also vary considerably with the richness of mix and the type and strengths of concrete of aggregates. Workability of HPCs depends upon the type of cement and its compatibility with chemical admixtures, shape of aggregate, method of mixing of ingredients of HPCs, etc. Thus, the properties of materials and mix preparation techniques have very high influence on the HPC mixes, suitable mix proportions cannot be suggested for HPCs. Therefore, any mix design procedure of HPCs can strictly be only a guideline and a separate development of HPC mix in the laboratory for the various ingredients, type of structure and concreting conditions etc., is very much essential. Hence, the HPC mix design can be only applicationspecific. It should be noted that the strength increase as the w/c is reduced (provided the compatibility of concrete is maintained), and that for a given w/c, the strength is decreased as a mix is made richer (by adding more cement) beyond a limit. Therefore, the advantage of increase in strength due to lowering of the w/c, which also reduces consequently the workability. Hence, the HPCs require approaches other than the increase of cement content in order to achieve the high strength. Page 17

High strength (M70) and High Performance Concrete

Though the strengths are not always true indicators of durability, the high strength associated with the HPCs generally tend to impart also high durability to them, due to reduced w/b and use of pozzolanic admixtures. OBJECTIVE

To achieve high strength concrete (M70) without compromising the workability of concrete . Normally when we try to achieve very high strength the mix becomes very stiff and it can ’t be pumped on the site .Thus our main aim was to achieve the desired strength with desired workability and other properties like low permeability ,high durability etc. CRITICAL STUDY OF THE FOLLOWING

Variation in compressive strength with respect to water cement ratio and varying proportions of cementation materials.

MATERIAL USED 

Cement(OPC Cement 43 grade)



Fly Ash



Micro Silica



Coarse Aggregates(20mm & 10mm)



Fine Aggregates



Water



Admixture (Glenium 51)

Mix Design Detail of M-70

Target Mean Strength Page

18

High strength (M70) and High Performance Concrete

Fck =fck+1.65 s =70+1.65*5 = 78.25 MPa

Where, fck ’ – target average compressive strength 28 days. fck- Characteristic compressive strength at 28 days “S” is taken 5 for M30 or above as per IS 10262

Design for 1m3 batch. From Table-2 IS 10262 Maximum water content for 20 mm aggregate – 186 kg for (slump 25mm to 50mm) Estimation of Water Content for 75mm SLUMP. =186+ (15/100)*186 =186+27.9 =213.9 kg/m3 From trials it was found that admixture (super plasticizer) Glenium SKY 51 reduced water content by 30%. Hence arrived water content

=213.9*0.7 =149.73 kg/m3

*Note: modification in water content has been done in accordance with the standard lab result various trial mixtures for required slump/flow requirement and strength, which are not specified in IS codes. Calculation of Cementations Material From trial an error water cement ratio was found 0.26 Cementations Content:

149.73/0.26

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High strength (M70) and High Performance Concrete

= 576 kg/m3 Content of OPC

:

-0.77*576 =434 Kg/m3

Content of Fly Ash :

-0.17*576 =98 kg/m3

Micro Silica

:

0.06*576 =35 kg/m3

Volume of Coarse Aggregates and Fine Aggregates Volume of 20mm aggregates

= 0.23

Volume of 10mm aggregates

= 0.35

Volume of Fine Aggregates

= 1-(0.23+0.35) =0.42

Mix Calculation Mix calculation per unit volume of Concrete as follows: Volume of Concrete

:

1m3

Volume of Cement

:

(Mass of Cement /Specific gravity)*(1/1000) = (434/3.14)*(1/1000) =0.138 m3

Volume of Fly Ash

:

(Mass of Fly Ash/Specific gravity)*(1/1000) = (98/1.93)*(1/1000) =0.050 m3

Volume of Micro silica

:

( Mass of Micro silica/ specific Gravity)*(1/1000) = (35/2.2)*(1/1000) = 0.0159 m3

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High strength (M70) and High Performance Concrete

Volume of Water

= (Mass of Water/Specific Gravity of Water)*(1/1000) = (149.73/1)*(1/1000) =0.149 m3

Volume of Admixture Admixtures)*(1/1000)

= (Mass of Glenium sky 777/Specific Gravity of = (7.02/1.1)*(1/1000) = 0.00638 m3

Volume of All in one Aggregates

: (1-(0.138+0.050+0.0159+0.150)) =0.6471m3

Mass of Course Aggregates 20 mm: =0.6471*volume of 20mm aggregates*Specific gravity*1000 =0.6471*0.23*2.60*1000 =386 kg/m3 Mass of Coarse aggregates 10 mm: = 0.6471*volume of 10mm aggregates *specific gravity*1000 =0.6471*0.35*2.59*1000 =586 kg/m3 Mass of fine aggregates: = 0.6471 *volume of fine aggregates* specific gravity*1000 =0.6471*0.42*2.55*1000 =693 kg/m3

Obtain Mix Proportion for Trial Mix Cement

:

434 kg/m3

Fly Ash

:

98 kg/m3

Micro Silica

:

35 kg/m3

Water

:

149 kg/m3

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High strength (M70) and High Performance Concrete

Coarse aggregates 20 mm

:

356 kg/m3

Coarse aggregates 10 mm

:

586 kg/m3

Fine aggregates

:

693 kg/m3

Water Cement Ratio

:

0.26

Trial Mix Batch Of 0.03 Cement

:

13.02 kg

Fly Ash

:

2.94 kg

Micro Silica

:

1.05 kg

Water

:

4.47 kg

Coarse aggregates 20 mm

:

10.95 kg

Coarse aggregates 10 mm

:

17.58 kg

Fine aggregates

:

20.76 kg

Water Cement Ratio

:

0.26

Two other trial mixes were as follows

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High strength (M70) and High Performance Concrete

BATCH A

Cement

:

13.60 kg

Fly Ash

:

1.7 kg

Micro Silica

:

1.7 kg

Water

:

4.47 kg

Coarse aggregates 20 mm

:

10.95 kg

Coarse aggregates 10 mm

:

17.58 kg

Fine aggregates

:

20.76 kg

Water Cement Ratio

:

0.26

BATCH B

Cement

:

11.90 kg

Fly Ash

:

3.40 kg

Micro Silica

:

1.70 kg

Water

:

4.47 kg

Coarse aggregates 20 mm

:

10.95 kg

Coarse aggregates 10 mm

:

17.58 kg

Fine aggregates

:

20.76 kg

Water Cement Ratio

:

0.26

Laboratory Tests

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High strength (M70) and High Performance Concrete

Various laboratory tests were performed during our training period has be listed below with their obtained values and permissible limit. 1. Determination of Specific Gravity by Pycnometer Method. Permissible Limit-

2.4 to 2.9

Obtained Values Coarse Aggregate

:

2.6

Fine Aggregate

:

2.59

2. Determination of Moisture Content Of Aggregates

Permissible Limit: Less than 2% for coarse aggregate and less than 2.3% for fine aggregates. Obtained Value Coarse aggregate:

0.5%

Fine aggregate :

1.5%

3. Determination of Impact Value of Coarse aggregate Permissible Limit :

30%

Obtained Value :

18.76%

3. Crushing Test Permissible Limit :

30%

Obtained Value :

17.67%

3. Determination of Initial and Final Setting Time of Cement

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High strength (M70) and High Performance Concrete

Permissible Limit:

Initial Setting Time: As per IS Code it should not be less than 30 minutes for general purpose. Final Setting Time: As per IS Code it should Not be more than 10 Hours. Obtained Value Initial Setting Time: 48 minutes Final Setting Time: 6 hours 47 minutes.

Determination of Sieve Analysis of Aggregates

Sieve Analysis Fine Aggregates Sieve Size (mm)

% passed

Weight

Percentage

Cumulative

10

0

0

0

100

Permissible Limit

Remark

4.75

172

9.11

9.11

90.89

90 to 100

2.36

160

8.48

17.59

82.41

75 to 100

1.18

323

17.11

34.70

65.3

55 to 100

600 micro

243

12.11

46.81

53.19

35 to59

300 micron

752

39.85

86.66

13.34

8 to 30

150 micron

196

10.38

97.04

2.96

0 to 10

Pan

41

2.17

99.21

0.79

100

Passed

0

Page 25

High strength (M70) and High Performance Concrete

Sieve Analysis 20 mm Aggregates Sieve Size (mm)

Weight

Percentage

Cumulative

% passed

Permissible Limit

Remark

25

0

0

0

100

100

20

1858.995

9.81

9.81

90.19

85 to 100

10

1456.308

84.85

94.66

5.34

0 to 20

4.75

51.7335

4.73

99.39

0.61

0 to 5

11.5595

0.61

100

0

PAN

Passed

0

Sieve Analysis 10 mm Aggregates Sieve Size (mm)

Weight

Percentage

Cumulative

Remark

0

0

0

100

100

20

1858.995

9.81

9.81

90.19

85 to 100

10

1588.958

83.85

93.66

6.34

0 to 20

4.75

104.7935

5.53

99.19

0.81

0 to 5

15.3495

0.81

100

0

Preparation of trial mix.

26

Permissible Limit

25

PAN

Page

% passed

0

Passed

High strength (M70) and High Performance Concrete

Page 27

High strength (M70) and High Performance Concrete

Page

28

High strength (M70) and High Performance Concrete

Snaps of Compressive Strength Test

Page 29

High strength (M70) and High Performance Concrete

Page

30

High strength (M70) and High Performance Concrete

[TYPE A QUOTE FROM THE DOCUMENT OR THE SUMMARY OF AN INTERESTING POINT. YOU CAN POSITION THE TEXT BOX ANYWHERE IN THE DOCUMENT. USE THE DRAWING TOOLS TAB TO CHANGE THE FORMATTING OF THE PULL QUOTE TEXT BOX.]

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High strength (M70) and High Performance Concrete

Test Results

Page

32

High strength (M70) and High Performance Concrete

Graphical Representation of Data Page 33

High strength (M70) and High Performance Concrete

28 days Strength Vs W/C Ratio 70

60 )

a 50 P ( M h t

g 40 n e rt S e

v is 30 s re p m o 20 C

10

0 0.25

0.26

0.27

0.28

0.29

W/C ratio

Page

34

0.3

0.31

0.32

0.33

High strength (M70) and High Performance Concrete

Variation of in 7 day strength with change w/c ratio

46 44 42 40 38 36 34 32 w/c w/c w/c w/c w/c w/c (0.26) (0.27) (0.28) (0.29) (0.30) (0.32)

C:FA:MS (78:17:5) C:FA:MS (70:20:10) C:FA:MS (80:10:10)

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High strength (M70) and High Performance Concrete

Variation of in 28w/c dayratio strength with change 80 C:FA:MS (78:17:5) C:FA:MS (70:20:10)

60 40 20 0 w/c w/c w/c w/c w/c w/c (0.26) (0.27) (0.28) (0.29) (0.30) (0.32)

Page

36

C:FA:MS (80:10:10)

High strength (M70) and High Performance Concrete

Variation of 7 day strength at 46 44 42 40 38 36 34 32

C:FA:MS (78:17:5) C:FA:MS (70:20:10) C:FA:MS (80:10:10) W/c (0.28)

W/c (0.27)

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High strength (M70) and High Performance Concrete

Variation of 28 day strength at a particular w/c ratio with varying proportions of

80 C:FA:MS (78:17:5)

60 40 20 0 w/c (0.28)

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38

w/c (0.27)

C:FA:MS (70:20:10) C:FA:MS (80:10:10)

High strength (M70) and High Performance Concrete

Conclusion 

Our target was to achieve M 70 grade concrete but we could reach up to a compressive strength of 71.21MPa.



But due poor workmanship and professional inexperience we were not able to achieve desired compressive strength, however we were able to achieve compressive Strength of 71.21 MPa which was quite closer to our results. Added to that we carried outs trial mixes at various water cement ratios(0.32-0.26) which helped us in understanding the behavior of concreter at lower water cement ratio which was displayed in graphs in previous slides.



We also understood there are various uncertainties associated with the concrete mix design and even smaller or minor things could be crucial and may affect the behavior of concrete.

References

Page 39

High strength (M70) and High Performance Concrete

High Strength Concrete Journals IS Code: 10262 Ultra High Performance Concretes. Association Francaise de Genie Civil, 2002. Concrete canvas

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