D.V .Bhavanna Rao M.Tech., F.I.E., Retired R&B Chief Engineer E-mail:
[email protected] Phone: +919494440202
for all my presentations, please visit http://aproadbuildqa.blogspot.com
Important Publications for Rural Roads 1.Specifications for Rural Roads, MORD (2004). 2.Rural Roads Manual IRC:SP:20-2002. 3. MORD Quality Assurance Handbook for Rural Roads Volume I and II :2007 4.Hill Road Manual: IRC:SP:48-1998. 5.IRC:SP: 72-2007: Guidelines for design of flexible pavements for low volume Rural Roads 6. IRC:SP: 62-2004 Guidelines for Design of Rigid Pavements for Rural Roads
300 Earth works 301 Embankment construction 302 Earth work in cutting 303 Subgrade construction 304 Rock cutting 305 Excavation for structures 306 Flyash Embankment construction 307 Surface drains 308 Soil erosion and sedimentation control 309 Turfing with sods 310 Seeding and mulching
400 Granular Sub-bases, Bases & surfacings 401 Granular Sub - Base 402 Gravel/Soil – Aggregates base and surface course 403 Lime treated soil for improved Sub – Grade / sub base 404 Cement treated Soil sub-base/ base 405 Water Bound macadam sub-base/ bases/surfacing 406 Wet Mix Macadam base 407 Shoulder construction 408 Local materials for road construction 409 Lime – Flyash stabilised soil sub-base 410 Industrial wastes for road construction 411 Crusher – Run macadam base 412 Brick soling 413 Stone set pavement
500 Bituminous costruction 501 Preparation of surface. 502 Prime coat over Granular Base 503 Tack coat 504 Bituminous Macadam 505 Built-up spray grout 506 Modified penetration macadam 507 Surface dressing 508 20mm Thick premix carpet 509 Mix seal surfacing 510 Seal coat 511 Supply of stone aggregates for pavement courses 512 Modified bitumen
Other Important Sections in MORD Specifications 200 Site Clearance 600 Brickwork for Structures 700 Stone masonry for Structures 800 Concrete for Structures 900 Formwork and surface finish for structures 1000 Steel reinforcement 1100 Pipe culverts 1200 RCC slab culverts and minor bridges 1400 Cement Concrete Causeways 1500 Cement Concrete Pavement 1600 Hill Road Construction 1800 Quality Control 1900 Maintenance
Important Sections in IRC:SP:20-2002 Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter
1: Planning and Alignment 2: Geometric Design Standards 3: Climate and Environment 4: Road Materials 5: Pavement design 6: Road Drainage 7: Culverts and Small Bridges 8: Construction and Specifications 9: Use of Waste materials 10: Quality Control in Construction 11: Maintenance 12: Souces of Finance
Typical cross section in plain and rolling terrain
shoulder
Base Sub base eeeeEeeee Sub-Grade (300mm)
shoulder
Embankment
Typical Pavement Cross Section
Pavement thickness chart as per IRC: SP 20 2002
Pavement thickness as per IRC: SP 20 2002 CBR
2%
3%
4%
5%
6%
Crust
0 to 15 CVPD
15 to 45 CVPD
45 to 150 CVPD
150 to 450 CVPD
Base
150
150
225
225
Sub base
275
365
370
455
Base
150
150
150
225
Sub base
200
265
330
320
Base
150
150
150
150
Sub base
125
200
260
315
Base
150
150
150
150
Sub base
100
165
210
260
Base
150
150
150
150
Sub base
60
115
150
175
Pavement thickness as per IRC: SP 20 2002 CBR
7
10%
15%
20%
Crust
0 to 15 CVPD
15 to 45 CVPD
45 to 150 CVPD
150 to 450 CVPD
Base
150
150
150
150
Sub base
60
115
150
175
Base
150
150
150
150
Sub base
30
70
85
125
Base
150
150
150
150
Sub base
nil
30
50
75
Base
150
150
150
150
Sub base
nil
nil
30
50
IRC: SP 72 – 2007, Pavement Design Catalogue. CBR = 2% Cumulative ESAL applications
Bituminous Surface treated WBM/CRMB
Base of gravel, WBM, CRMB of CBR not less than 100%
10,000 to 30,000
Nil
nil
200
nil
100
30,000 to 60,000
75
nil
150
nil
100
60,000 to 1,00,000
75
100
nil
100
100
1,00,000 to 2,00,000
75
100
nil
100
150
2,00,000 to 3,00,000
75
100
nil
150
150
3,00,000 to 6,00,000
75
100
nil
225
150
6,00,000 to10,00,000
75
150
nil
200
225
Gravel Base of CBR not less than 80%
Granular Sub Base of CBR not less than 20%
Modified soil or sub grade of CBR not less than 10%
T04%IRC: SP 72 – 2007, Pavement Design Catalogue. CBR = 3 to 4%
Cumulative ESAL applications
Bituminous Surface treated WBM/CRMB
Base of gravel, WBM, CRMB of CBR not less than 100%
10,000 to 30,000
Nil
nil
200
nil
nil
30,000 to 60,000
nil
nil
275
nil
nil
60,000 to 1,00,000
75
100
nil
150
nil
1,00,000 to 2,00,000
75
100
nil
100
100
2,00,000 to 3,00,000
75
100
nil
100
150
3,00,000 to 6,00,000
75
150
nil
100
150
6,00,000 to10,00,000
75
150
nil
150
150
Gravel Base of CBR not less than 80%
Granular Sub Base of CBR not less than 20%
Modified soil or sub grade of CBR not less than 10%
T04%IRC: SP 72 – 2007, Pavement Design Catalogue. CBR = 5 to 6%
Cumulative ESAL applications
Bituminous Surface treated WBM/CRMB
Base of gravel, WBM, CRMB of CBR not less than 100%
10,000 to 30,000
Nil
nil
175
nil
nil
30,000 to 60,000
nil
nil
250
nil
nil
60,000 to 1,00,000
nil
nil
275
nil
nil
1,00,000 to 2,00,000
75
100
nil
125
nil
2,00,000 to 3,00,000
75
100
nil
150
nil
3,00,000 to 6,00,000
75
100
nil
100
100
6,00,000 to10,00,000
75
150
nil
100
100
Gravel Base of CBR not less than 80%
Granular Sub Base of CBR not less than 20%
Modified soil or sub grade of CBR not less than 10%
T04%IRC: SP 72 – 2007, Pavement Design Catalogue. CBR = 7 to 9%
Cumulative ESAL applications
Bituminous Surface treated WBM/CRMB
Base of gravel, WBM, CRMB of CBR not less than 100%
10,000 to 30,000
Nil
nil
150
nil
nil
30,000 to 60,000
nil
nil
175
nil
nil
60,000 to 1,00,000
nil
nil
225
nil
nil
1,00,000 to 2,00,000
75
100
nil
100
nil
2,00,000 to 3,00,000
75
100
nil
125
nil
3,00,000 to 6,00,000
75
100
nil
150
nil
6,00,000 to10,00,000
75
150
nil
150
nil
Gravel Base of CBR not less than 80%
Granular Sub Base of CBR not less than 20%
Modified soil or sub grade of CBR not less than 10%
T04%IRC: SP 72 – 2007, Pavement Design Catalogue. CBR = 10 to 15%
Cumulative ESAL applications
Bituminous Surface treated WBM/CRMB
Base of gravel, WBM, CRMB of CBR not less than 100%
10,000 to 30,000
Nil
nil
125
nil
nil
30,000 to 60,000
nil
nil
150
nil
nil
60,000 to 1,00,000
nil
nil
175
nil
nil
1,00,000 to 2,00,000
75
150
nil
nil
nil
2,00,000 to 3,00,000
75
100
nil
100
nil
3,00,000 to 6,00,000
75
100
nil
125
nil
6,00,000 to10,00,000
75
150
nil
125
nil
Gravel Base of CBR not less than 80%
Granular Sub Base of CBR not less than 20%
Modified soil or sub grade of CBR not less than 10%
Embankment Construction 1.Embankment with natural earth
2. Embankment with Coal Ash a. Fly Ash b. Pond Ash c. Bottom Ash
Sub Grade Construction 1.Sub Grade with natural earth 2. Sub Grade with stabilised earth a. Stabilisation with sand and lime b. Stabilisation with coal ash c. Stabilisation with soft aggregates d. Stabilisation with gravel / moorum e. Stabilisation with cement
The following types of material shall be considered unsuitable for embankment, sub grade and shoulders: (i) Material from swamps, marshes and bogs (ii) Peat, log, stump and perishable material; soil classified as OL, OI, OH or Pt as per IS:1498. (iii) Materials susceptible to spontaneous combustion. (iv) Clay having liquid limit exceeding 70 and plasticity index exceeding 45. (v) Material with salts resulting in leaching action e.g. Soils of pH > 8.5). (vi) Expansive clay with free swelling index exceeding 50 per cent (vii) Materials in a frozen condition. (viii) Fill materials with a soluble sulphate content exceeding 1.9 gm of sulphate, (expressed as SO3) per litre, if deposited within 500 mm or other distance described in the Contract, of concrete, cement bound materials or other cementitious materials forming part of permanent works. (ix) Material with a total sulphate content (expressed as SO3) exceeding 0.5 per cent by mass, if deposited within 500 mm or other distance described in the Contract, of metallic items forming part of permanent works
MORD 301 Embankment Requirements Liquid limit < 70%, Plasticity Index< 45%,FSI < 50% MDD(min):1.44 g/cc up to 3m height and 1.52vg/cc for
embankment > 3m height. In case of fly Ash minimum MDD is reduced to 0.9 g/cc as per IRC Special Publication No.58 Breaking clods: 75mm maximum Moisture content: +1% or -2% of OMC for sandy / silty soils
and OMC to OMC + 2% for clayey / BC soils Maximum layer thickness: 200mm (vibratory roller) or 150mm in case of smooth wheeled roller Trimming: additional width of 0.6m on either side Relative compaction: 97%
MORD 303 Sub Grade Requirements Existing sub grade: If sub grade CBR is less than 2%, a capping layer of 100mm thick with 10% CBR soil is to be provided and a CBR of 2% is to be taken for crust design
New sub grade and Shoulders: MDD (min) is 1.65 g/cc Moisture content: +1% or -2% of OMC Relative Compaction: 100%
DO’s
Don’ts
1. Discourage borrow pits along the road; where permitted, ridges of minimum 8 m width should be left at intervals not exceeding 300 m. Small drains should be cut through the ridges to facilitate drainage. 2. The depth of borrow pits should be so regulated that their bottom does not cut an imaginary line having a slope of 1 vertical to 4 horizontal projected from the edge of the final section of the bank, the maximum depth in any case being limited to 1.0 m. 3. Do maintain a camber/ cross fall of 4 percent during construction for effective drainage and prevention of Ponding of water. 4. The area of the embankment foundation should be kept dry. Test the material (soil) for its suitability for use in the embankment at least seven days before commencement of earthwork. Tests should include soil. classification test data and data regarding maximum dry density, OMC, and CBR (soaked and un soaked). 5. For widening of existing embankment start earth work from toe line.
1. Do not allow borrow pits within a distance equal to the height of the embankment subject to a minimum of 1.5 m from the toe of the road embankment. 2. Do not allow borrow pits within 800 m of towns or villages. 3. Do not use unsuitable material for embankment construction. 4. Do not allow construction or other vehicular traffic over the prepared surface of embankment/ sub-grade. 5. Do not place successive layers of embankment until the previous layer has been thoroughly compacted and duly approved by Engineer. 6. Do not allow any damage to works, crops or other property while discharging stagnant water found in embankment foundation. 7. Do not allow dumping of earth from top to widen an existing embankment.
Appropriate Technology and machinary For Earthwork and Subgrade Construction 1. For clearing, grubbing and excavation : Rippers towed by agricultural tractor 2. For hauling of earth : Agricultural tractor-trailer 3. For spreading of soil in layers : Spreading blades attached to agricultural tractor 4. For adding water : Water Bowser towed by agricultural tractor 5. For mixing of soil with water : Agricultural tractortowed disc harrows 6. For compaction in earthwork and : 80-100 kN static smoothsubgrade construction wheeled road roller for compacted thickness of 100 mm.
Loading of embankment material at borrow source
Dumping of embankment material
Preparation of embankment
Rapid Determination of Moisture Content from Gas Pressure developed by the Reaction of Calcium Carbide with the Free Water of the Soil
Loose earth shall not be allowed to soak.
watering of embankment material
Field density test for embankment layers
Dumping of sub grade material
Moisture content versus Dry density relationship for a soil of poorly graded sands with little or no fines SP 1.86 1.84 1.82
Moisture Content %
Dry Density g/cc
3.12
1.74
4.3
1.77
5.41
1.79
7.3
1.85
1.74
12.85
1.757
1.72
15.71
1.69
1.7
1.8 1.78
Se…
1.76
1.68
0
OMC = 7.3 % MDD = 1.85 g/cc
5
10
15
20
grading of sub grade material
Rolling of sub grade material
Field density testing of sub grade material
Fly ash for road embankment Ideally suited as backfill material for urban/ industrial areas and areas with weak sub soils Higher shear strength leads to greater stability Design is similar to earth embankments Intermediate soil layers for ease of construction and to provide confinement Side slope erosion needs to be controlled by providing soil cover Can be compacted under inclement weather conditions 15 to 20 per cent savings in construction cost depending on lead distance
Fly ash for road embankment Earth Cover
Earth Cover Bottom ash or Pond ash
Typical cross section of fly ash road embankment
Approach embankment for second Nizamuddin bridge at Delhi
Length of embankment - 1.8 km Height varies from 6 to 9 m Ash utilised - 1,50,000 cubic metre Embankment opened to traffic in 1998 Instrumentation installed in the embankment showed very good performance Approximate savings due to usage of fly ash is about Rs.1.00 Crore
Approach embankment for second Nizamuddin bridge at Delhi
MORD Specification 401 Granular Sub Base Minimum CBR = 20% (on economical basis,15% may be permitted by competent authority) Material in mix passing 425 micron sieve shall have Liquid limit less than 25% Plasticity index less than 6% Material passing 75 micron sieve shall be less than 10%. (less than 5% on clayey sub grades) Material in the mix shall satisfy specified grading Wet Aggregate Impact value shall be less than 50% Layer thickness: 100 mm compacted with smooth wheeled roller 225 mm compacted with vibratory roller Moisture content: + 2% to – 2% of OMC Relative compaction: 100% ( Standard Procter’s test)
Table 400-1, MORD Specifications for Rural Roads Grading for Granular Sub-Base materials Percent by weight passing through the IS sieve IS Sieve Designation Grading I Grading II Grading III
75.0 mm
100
53.0 mm
--
--
100
26.5 mm
55-75
50-80
100
4.75 mm
10-30
15-35
25-45
0.075 mm
< 10
< 10
< 10
1) Liquid limitt < 25% and plasticity index < 6% 2) On clayey sub grade % passing on 75 micron sieve shall not exceed 5% 3) Wet Aggregate Impact Value shall not exceed 50%
Methodology 1. Obtain materials from approved sources. The material should be natural sand, moorum, gravel,crushed stone, crushed slag, brick metal, kankar or a combination thereof and it shall conform to grading and physical requirements indicated in Table 401.1 2. The sub-base material should be spread in layers not exceeding 100 mm compacted thickness. If suitable vibratory rollers are available, the compacted thickness of layer can be upto a maximum of 225 mm. 3.When the sub-base material consists of a combination of materials, mixing shall be done mechanically by the mix-in-place method, except for small sized jobs. 4. Each layer shall be uniformly spread and thoroughly compacted. Spreading and compaction shall be carried out as per Clause 401.4.2 of the MORD Specifications. 5. Approval of the Engineer should be obtained for each layer. Such an approval would require surface level and compaction control tests. 6. The earthen shoulders should be constructed simultaneously with the sub-base construction.
DO’s
1. Ensure uniform mixing of GSB material and water by mechanical means like tractor towed implements. 2. Ensure that on clayey sub grades, the percent fines passing 75 micron in the GSB material do not exceed 5 percent. 3. Do provide aggregate plugs at the exposed edges of GSB where extended over the full formation width. 4. Look for soft patches, if any, and rectify them by removing or adding fresh material and compacting the same thoroughly.
Don’ts
1. Do not permit organic or other deleterious materials. 2. Do not use materials, which do not conform to the specified requirements, shall not be used. 3. Do not allow rejected material to remain at site to prevent its reuse. The rejected material shall be marked with lime.
Preparation of Granular Sub base mix using 45% gravelly soil, 35% sand and 20% grade III metal
Construction of Granular Sub base mix using 45% gravelly soil, 35% sand and 20% grade III metal
Gravel associated GSB (mixture of gravelly soil (45%), metal (20%) and sand (35%) is creating lot of problems in execution during rains. It is preferable to opt for GSB without any gravelly soil
Mud
pumping
Definition of sand and gravel as per Code IS: 1490 – 1987 Sand and gravel are defined as Cohesion less aggregates of angular, sub-angular, subrounded, rounded, flaky or flat fragments of more or less unaltered rocks or minerals. According to the system, gravel is the fraction of the material between 80mm IS sieve size and 4.75mm IS sieve size. Sand is a fraction of the material between 4.75mm IS sieve size and 75 micron IS sieve size.
River gravel along Wankidi vaagu across which is being constructed in km 17/10 of Wankidi Kagaznagar in Adilabad District. This type of material satisfies gravel requirements as per IS code or MORT&H specifications. AIV = 14%. It satisfies grading III of table 400 – 2 for Granular Sub Base
Layer of adsorbed water surrounding a clay particle. Sliding of such particles over one another results in plasticity
Position after 24 hours of adding water
Natural gravelly soil LL = 38%, PI = 18%
Total Absorption of particles indicate the presence of negative charged particles in the gravelly soil. It indicates high PI and LL values. It proves that the above sample is earthen material only but not gravel or moorum. Use of such soil presuming it as gravel is causing damage and poor condition of Village Roads, Major District Roads, State Highways and National Highways. Highway Engineers must be able to differentiate between earth and gravel
GSB using crushed quarry spoils and granite for Pushkaram work in Narsapur in WG Dt. Similar mix is being used as GSB in NHAI works. This type of mix eliminates all problems associated with gravel combinations
Another view of GSB without gravel in Narsapur Drainage: Excellent, CBR: more than 60%
GSB with gravelly soil (45%), stone dust (35%) and metal (20%) also caused problems when executed during rainy season
GSB using gravel with some stone content being done in 4-laning of NH5 in Srikakulam District. Here, it contains lot of fines with high Plasticity Index value. It may give the required CBR but fails in plasticity
GSB with HBG materials as per Grading III of MORD table 400-1. Stone dust and 6mm to 10mm chips are mixed to satisfy the grading. It is producing CBR of more than 30%
Moisture content versus Dry density relationship for GSB with HBG crushed aggregates confirming to Grading III of table 400-2 2.28
Moisture Content %
Dry Density g/cc
2.87
2.14
3.73
2.17
2.26
2.24
2.22
2.2
5.4
2.22
7.69
2.26
9.07
2.165
2.16
10.39
2.11
2.14
Series1
2.18
2.12
OMC = 7.69 % MDD = 2.26 g/cc
2.1 0
2
4
6
8
10
12
GSB using HBG materials as per grading III of MORD table 400-1. Stone dust, 6mm chips and 10 mm chips are used. It is good for drainage and produce CBR above 30%
GSB using HBG materials as per MORD grading III of table 400-1. Stone dust, 6mm chips and 10 mm chips are used. It is good for drainage and produce CBR above 30%. NABARD work: Narakoduru Anantavarappadu road, Guntur District
GSB using HBG materials as per grading III of MORD table 400-1. Stone dust, 6mm chips and 10 mm chips are used. It is good for drainage and produce CBR above 30% Machavaram village limits in Guntur district
GSB with alternate materials WBM with grade I HOG metal without blindage. This is an excellent GSB option. It gives very high CBR values(>50%) and also serves as a good drainage layer
MORD Specifications 402: Gravel/ Soil-Aggregate 403: Lime treated soil for improved sub grade/ sub-base 404: Cement treated soil sub-base/ base 408: Local materials for road construction
409: Lime-Fly ash stabilised soil sub-base 410: Industrial Wastes for Road Construction
MORD 408 Local materials for Road Construction Table 400–13: Manner of using local aggregates in rural road works State of occurrence of material
Manner of using in pavement crust
Test/ quality requirements
In block or large discrete particles such as kankar, laterite, dhandla etc.
As WBM without screenings/ binder after breaking into sizes
Wet AIV ≤ 50%, 40% and 30% for sub-base, base and surfacing
as granular layer for sub-base or base or surfacing
PI: 4 to 10 for surfacing, PI< 6 for lower courses. Soaked CBR for strength
As discrete particles mixed with appreciable Directly as soil-gravel amount of soil such as soil mix for sub-base or gravel mixtures, quarry base or surfacing wastes etc
Material well graded. Other requirements as above
Graded form without appreciable amount of soil, such as naturally occurring soils
Base Requirements as per IRC: SP 20 - 2002 Minimum thickness of base: 150mm Requirements of Base Courses: Densely Compacted layers with hard, durable, angular and non-plastic materials capable of resisting heavy loads, resistance to lateral movement and transmission of reduced uniform load distribution to sub base layers
Base Courses: Wet Mix Macadam Crusher Run Macadam Water Bound Macadam Dry Lean Concrete Requirements of Base Courses: Densely Compacted layers with hard, durable, angular and non-plastic materials capable of resisting heavy loads, resistance to lateral movement and transmission of reduced uniform load distribution to sub base layers
WMM
WBM with gravelly soil blindage
WBM with screenings and binder
CRM
Sizes Of Coarse Aggregates As Per Apss Table 1501-A Normal Size
Wholly passing through sieve of square mesh of size
Wholly retained an a sieve of square mesh of size
80 mm
100 mm
63 mm
63 mm
80 mm
50 mm
50 mm
63 mm
40 mm
40 mm
50 mm
25 mm
25 mm
40 mm
20 mm
20 mm
25 mm
12.5 mm
12.5 mm
20 mm
10 mm
10 mm
12.5 mm
6.3 mm
6.3 mm
10 mm
2.36 mm
Table 500-17, MORD size requirements for coarse stone aggregates Nominal size of aggregate
Sieve size through which Sieve size on which aggregates wholly pass aggregates wholly retained
75mm
106mm
63mm
63mm
90mm
53mm
45mm
53mm
26.5mm
26.5mm
45mm
22.4mm
22.4mm
26.5mm
13.2mm
13.2mm
22.4mm
11.2mm
11.2mm
13.2mm
6.7mm
6.7mm
11.2mm
5.6mm
MORD Table 400-7, Physical Requirements of Coarse Aggregates for WBM Test Sub-base Base Surfacing AIV < 50% < 40% < 30% FIV < 30% < 25% < 20% Soundness Test when water absrption > 2% Loss with sodium sulphate < 12% Loss with magnesium < 18% sulphate For Screenings: LL < 20%, PI < 6% and % passing 75 micron sieve < 10% (405.2.8) For binder: PI < 6% for sub base and base. PI shall be from 4 to 10% for binder for srfacing (405.2.9)
Coarse Aggregates: Gr-I to Gr-III, Screenings: Type-A: 6mm and 10mm, Type-B: Stone Dust Binder: Stone Dust. Gravel for WBM as wearing course Process of WBM
Spreading Metal > Sectioning and Dry Rolling > Light Sprinkling of Water > rolling > Application of Screenings > Brooming > Rolling > Watering & Sweeping > Rolling > Application of Binder > Sprinkling of Water & Sweeping > Rolling > Setting and Drying
DO’s
Don’ts
1. Check aggregates for Soundness test when water absorption is more than 2% 2. Soft aggregate should be tested for wet aggregate impact value. 3. Construct shoulders simultaneously along with WBM layers. 4. Use inverted choke over fine grained soil sub-grade. 5. Remove BT surface before WBM is laid on an existing black top road. 6. Remove defective macadam to full depth and replace by fresh material and re-compact.
1. Do not use any material derived from rocks e.g. phyllites, shales or slates. 2. Do not use local soil and clayey material as screenings or binding material unless it meats the requirements of PI mentioned 3. Do not use binding material if screenings are of crushable type. 4. Do not spread coarse aggregate more than 3 days in advance of any subsequent operations. 5. Do not roll if sub-grade is soft or yielding or causes a wave like motion while rolling. 6. Do not lay WBM layer on lime treated sub-base until it has attained its strength. 7. Do not use screenings to make up depressions. 8. Do not allow traffic till WBM is fully set.
Grade I HBG metal as per table 400 - 8
Cumulativ % IS Sieve passing
specified
125mm
100
100
90mm
92
90 - 100
63mm
45
25 - 60
45mm
8
0 - 15
22.4mm
3
0-5
Grade II HBG metal as per table 400 - 8
Cumulativ % IS Sieve passing
specified
90mm
100
100
63mm
94
90 - 100
53mm
50
25 - 75
45mm
7
0 - 15
22.4mm
3
0-5
Grade III HBG metal as per table 400 - 8
Cumulativ % IS Sieve passing
specified
63mm
100
100
53mm
97
95 - 100
45mm
80
65 - 90
22.4mm
8
0 - 10
11.2mm
2
0-5
MORD Table 400 - 9
Type of screenings Type A 13.2mm (6mm & 10mm chips) Type B 11.2mm (stone dust)
Type A screenings
IS Sieve 13.2mm 11.2mm 5.6mm 180 micron 11.2mm 5.6mm 180 micron
% passing 100 95-100 15-35 0-5 100 90-100 15-35
Type B screenings or binder
Sieve Analysis of stone dust with type B screenings sieve set Percent passing Sample 1
Sample 2
Sample 3
Specified passing for Type B Screenings
11.2m m
100
100
100
100
5.6mm
96.12
98.62
99.54
90 - 100
180 micron
24.52
17.83
20.82
15 - 35
IS Sieve
Stone screenings type
quantity/10Sqm
Binder per 10SqM
Gr I - 133/100mm
type A
0.27 to 0.3 cum
0.08 to 0.10 cum
Gr II – 100/75mm
type A
0.12 to 0.15 cum
-do-
type B
0.20 to 0.22 cum
Gr III 100/75mm
type B
0.18 to 0.21 cum
WBM
0.06 to 0.09 cum
Item
Coarse Aggregates
Type A screenings (6mm)
Type B screenings (dust)
Binder (dust)
Grad I WBM
1.21 cum
0.27 cum
nil
0.08 cum
Grade II WBM with type A screenings
0.91 cum
0.12 cum
nil
0.06 cum
Grade II WBM with type B screenings
0.91 cum
nil
0.20 cum
0.06 cum
Grade III WBM
0.91 cum
nil
0.18 cum
0.06 cum
Incorrect practice of WBM with gravelly soil blindage adopted over the years.
Spreading of metal using templates placed across the road about 6m apart.
Dry rolled surface
Making up of the surface irregularities of the metal surface
After dry rolling, spreading of screenings is in progress to fill voids in the coarse aggregates.
Brooming with hand brooms, to fill voids in the coarse aggregates
Sprinkling of water is in progress
Rolling after sprinkling of water
Application of binding material successively in two or more thin layers. Due to application of stone dust as screenings and binder internal friction between coarse aggregates is not getting reduced.
GR III WBM with stone screenings as per clause 405 of MORD
WBM using grade III HBG metal and crusher dust as type B screenings and binder
Surface of WBM with grade II HBG metal. Type A screenings used are 6mm and 10mm and binder is stone dust. Grade III collections in progres. Narakoduru Anantavarappadu road in Guntur District.
Surface of WBM with grade III HBG metal. Type B screenings and binder used is stone dust. Narakoduru Anantavarappadu road in Guntur District.
Table 400-11. Grading Requirements of Aggregates for the Wet Mix Macadam IS Sieve Designation
Per cent by weight passing the IS Sieve
53.00 mm
100
45.00 mm
95-100
22.4 mm
60-80
11.20 mm
40-60
4.75 mm
25-40
2.36 mm
15-30
600.00 micron
8-22
75.00 micron
0-8
WET MIX MACADAM
Materials : 40mm, 20mm , 12mm, 6mm &Stone Dust Mixing at Pug Mill with Water, Conveyed to Site, Spreading by Paver and Rolling. Relative Compaction = 98 %
DO’s 1. Ensure compliance of all material and plant requirements. 2. Check aggregate for soundness test when water absorption is more than 2 %. 3. Build shoulders simultaneously along with WMM layers. 4. Remove BT surface before WMM is laid on an existing road.
Don’ts 1. Do not use material other than crushed stone.
2. Do not allow segregation or pockets of coarse/fine material on the layer. 3. Do not allow any traffic on the WMM surface without covering it with a wearing course.
Pug mill for Wet Mix Macadam
Loading WMM into tipper at Pug mill
Laying of Wet Mix Macadam with paver
Moisture content versus Dry density relationship for Wet Mix Macadam 2.35
Moisture Content %
Dry Density g/cc
4.76
2.11
5.63
2.14
6.08
2.19
6.82
2.32
10.25
2.159
11.86
2.10
2.3
2.25
2.2
Series1
2.15
2.1
2.05
OMC = 6.82% MDD = 2.32 g/cc
0
5
10
15
Wet Mix Macadam on Mangalagiri Rayapudi road
BLACK TOPPED SURFACINGS Strengthening layers Bituminous Macadam Modified Penetration Macadam Wearing Courses Surface Dressing Open Graded Premix Carpet with seal coat Closely graded premix carpet or Mix Seal surfacing (hot mix process)
Requirements of BT Surfacing IRC:37, MORD Section 500 o High stability – resisting permanent deformation o Good durability and long life-resisting traffic abrasion o Good elastic properties o Good resistance to fatigue o Low permeability to water and air o Good workability when hot o Good skid resistance o Good riding quality o Acceptable level of noise under traffic o Economical in initial cost and maintenance
MORD 502.Prime Coat over granular base Application of single coat of low viscosity liquid bituminous material to an absorbent granular surface to any superimposed bituminous treatment MORD Table 500-1, Primer requirements Porosity Low
Surface WBM/WMM
Quantity kg/10sqm 7 - 10
Medium
Stabilised base
9 - 12
High
Gravel base
12 - 15
1) It coats and bonds loose mineral particles of granular surface 2) It water proofs the surface of the base by plugging capillary or un connected voids 3) It provides adhesion or bond between the granular base and bituminous layers
Methodology for Prime Coat 1. Bituminous primer should be slow setting bitumen emulsion, use of cutback being restricted to areas having sub zero temperature or for emergency operations. 2. The prime coat should be applied only on the top most granular base layer, over which bituminous treatment is to be applied. The granular base surface should be swept clean of dust and loose particles and where required, lightly and uniformly sprinkled with water to moist the surface. 3. The primer should be sprayed uniformly over the dry surface of absorbent granular base, using suitable bitumen pressure distributor or sprayer capable of spraying primer at specified rates and temperature so as to provide a uniformly unbroken spread of primer. Normal temperature range of spraying emulsion should be 20°C to 60°C. The rate of application depends upon the porosity characteristics of the surface to be primed and is given in above table.
DO’s 1. Use slow setting emulsion and restrict the use of cutback to subzero temperature conditions or emergency operations. 2. Use only pressure sprayers. 3. Preferably lay a trial section. 4. The Contractor to demonstrate at a spraying trial to ensure that the equipment is capable of producing a uniform spray.
Don’ts 1. Do not apply primer when the atmospheric temperature in shade is less than 10°C or when the weather is foggy, rainy or windy. 2. Do not allow pouring of primer using perforated cans. 3. Do not allow traffic on primed surface. 4. Do not apply bituminous material to a wet surface.
Check for rate of spread 20cm × 20cm × 3cm trays for binder collection
Prime coat over WMM
On WMM/WBM surface, prime coat followed by sand flushing is a better option to allow traffic for short duration
MORD 503.Tack Coat MORD Table 500-2, Rate of application of tack coat Type of surface
Bitumen emulsion Kg/sqm
Nominal bituminous surfaces
0.20 to 0.25
Dry and hungry bituminous surfaces
0.25 to 0.30
Granular surfaces treated with primer
0.25 to 0.30
Cement concrete pavement
0.30 to 0.35
Methodology for Tack Coat 1. Use a rapid setting bitumen emulsion for applying a tack coat, the use of cutback being restricted to areas having sub-zero temperature or for emergency applications. 2. The surface on which tack coat is to be applied should be clean, free from dust, dirt and any extraneous materials and dry. 3. The surface should be prepared as per sub-section 501. 4. The binder should be sprayed uniformly over the surface using suitable bitumen pressure sprayer capable of spraying bitumen and emulsion at specified rates and temperature so as to provide a uniformly unbroken spread of bitumen emulsion. For smaller jobs, a pressure hand sprayer may be used. Normal range of spraying temperature should be 20°C-60°C in case of emulsion and 50°C-80°C in case of cutback. The rate of application depends upon the type of surface and is given in above Table . 5. The surface should be allowed to cure until all the volatiles have evaporated.
DO’s 1. Plan the work so that no more than the necessary tack coat for the day’s operation is placed on surface.
Don’ts 1. Do not apply tack coat when atmospheric temperature is less than 10°C or when weather is foggy, rainy or windy.
2. Handle bituminous 2. Do not apply tack coat cutback carefully to avoid fire on a wet surface. mishap. 3. Do not allow any equipment or vehicles on Tack Coat.
MORD table 500-5,Manufacturing and Rolling Temperatures Minimum Rolling temp. ºC
Laying-ºC
Bitumen Penetration
Bitumen Mixing -ºC
Aggregate Mixing-ºC
Mixed Material ºC
35 (30-40)
160 to 170
160-175
170 Max
110 Min
140 Min
65 (60-70)
150 to 165
150-170
165 Max
100 Min
130 Min
90 (80-100)
140 to 160
140-165
155 Max
100 Min
130 Min
MORD 506 Modified Penetration Macadam (MPM) Rate of application for 10sqm area 75mm Description
Bituminous surface, cum
40mm size hand broken metal 12mm size chips
50mm
On WBM surface, cum
Bituminous surface, cum
On WBM surface, cum
0.9
0.6
0.18
0.18
AIV < 40% and FIV < 25% for coarse aggregates. Bitumen rate of application for 10sqm area (kg)
75mm
Description
Bitumen for grouting
50mm
Bituminous surface
On WBM surface
Bituminous surface
On WBM surface
20
20
17.5
17.5
Tack coat shall be as per clause 503 (table 500 -2)
1. Spread coarse aggregate of 40 mm size metal uniformly at the rate of 0.9 cum for 75 mm thickness (0.6 cum for 50 mm thickness) per 10 sqm area to proper camber/ super-elevation. Remedy all high spots and depressions by removing or adding aggregates. 2. Commence rolling with 80-100 kN rollers (three-wheel or tandem type), beginning from the edge and progressing towards the centre longitudinally. On super elevated portions, rolling should progress from lower to upper edge parallel to centre line of pavement. 3. Correct any irregularities noticed after the roller has passed over the whole area once by loosening the surface and removing or adding the coarse aggregates followed by rolling. Continue rolling till the entire surface has been rolled to desired compaction such that there is no crushing of aggregates and all roller marks have been eliminated. Each pass of roller should overlap not less than one-third of the track made in the preceding pass. 4. Heat bitumen (paving grade S-35 to S-90) to a temperature of 160°C to 180°C and spray uniformly on aggregate layer at the rate of 20 kg per 10 m2 for 75 mm thick layer and 17.5 kg per 10 m2 for 50 mm thick layer. 5. Immediately after application of bitumen, spread 12 mm size key aggregates at a uniform rate of 0.18 cum for 75 mm thickness (0.12 cum for 50 mm thickness) per 10 m2 so as to cover the surface completely and roll. Rolling should continue until the key aggregates are firmly embedded in position and stop moving under roller
DO’s 1. Ensure that aggregates conform to grading specified and are dry and clean at the time of laying. 2. Maintain the temperature of bitumen appropriate to the grade of bitumen. 3. Remove excessive deposits of binder during spray operation.
Don’ts 1. Do not undertake the work in foggy. rainy or windy weather or when the atmospheric temperature in the shade is less than l0°C. 2. Do not allow any traffic over Built up spray grout without laying wearing course or seal coat.
Modified Penetration Macadam (MPM). 40mm HBG metal at 0.6cum/10 sqm is spread, sectioned and rolled
Modified Penetration Macadam (MPM). 17.5 kg bitumen grouted and 0.18 cum/10sqm of 12mm key chips applied. Brooming is in progress.
Finished Modified Penetration Macadam (MPM) 50mm thick compacted layer.
504 BITUMINOUS MACADAM MORD Table 500-4, COMPOSITION IS Sieve (mm)
Cumulative % by weight ol aggregate passing
26.5
100
19
90 – 100
13.2
56 – 88
4.75
16 – 36
2.36
4 – 19
0.30
2 -10
0.075
0 -8
Bitumen content, % by weight of mixture
3.30 – 3.50
Bitumen Grade
35 to 90
AIV < 30%, FIV < 25% and WA < 2 %
Methodology for Bituminous Macadam 1. Prepare the base on which bituminous macadam course is to be laid and shape to the specified lines, grade and cross-section. 2. Apply tack coat over the base preparatory to laying of the bituminous macadam. 3. Bituminous Macadam should be prepared in a Hot Mix Plant of adequate capacity. Ensure manufacturing and rolling temperatures for Bituminous Macadam as specified. 4. Transfer the mixed material quickly to site of work and lay by means of an approved self-propelled mechanical paver. 5. Commence initial rolling with 80-100 kN rollers (three-wheel or tandem type), beginning from the edge and progressing towards the centre longitudinally. On super elevated portions, rolling should progress from lower to upper edge parallel to centre line of pavement. Thereafter, do intermediate rolling with vibratory or pneumatic tyred road rollers. This should be followed by final rolling while the material is still workable.
Methodology for Bituminous Macadam continued 6. Any high spots or depressions noticed after the roller has passed over the whole area once should be corrected by removing or adding premixed material. Rolling should recommence thereafter. Each pass should have an overlap of at least one-third of the track made in the preceding pass. Rolling should be continued till all rolIer marks have been eliminated. 7. For single lane roads no longitudinal joint is required, while for double-lane roads longitudinal joints may be required depending on the paver width. 8. For making longitudinal or transverse joint, cut the edges of the bituminous layer laid earlier to their full depth so as to expose fresh surface and apply a thin coat of binder. Lay adjacent new layer and compact flush with the existing layer. 9. Cover the bituminous macadam with the wearing course within a period of 48 hours. If there is any delay in providing wearing course the bituminous macadam surface should be covered with a seal coat before opening to traffic.
DO’s 1. Ensure that stone aggregate
Don’ts
1. Do not undertake the work in foggy, rainy or windy weather or conforms to the physical when the atmospheric temperature requirements and grading in the shade is less than 10°C. requirements and are dry and 2. Do not allow the difference in clean. temperature of binder and 2. In case the aggregate has poor aggregate to increase beyond 14OC affinity to bitumen use anti stripping at any time. agent with the approval of Engineer. 3. Do not allow the premix material 3. While transporting the mixture it to adhere to the roller wheels. (Do should be suitably covered by not use excess water for the purpose. Light sprinkling should do.) tarpaulin. 4. Do not use lubricating oil on the 4. Rolling operations should be wheels of the roller to prevent mix completed before the mix becomes from adhering. unworkable 5. Do not allow traffic until the mix 5. Maintain strict control on has been covered with a wearing temperature while mixing and rolling. course. 6. Regulate the rate of delivery of 6. Do not move roller at a speed material to paver to enable it to more than 5 km/h. operate continuously.
MORD 507 Surface Dressing Table 500 – 10: Size requirements of stone chips for surface dressing Type of construction
Size of chips
specification
Single coat surface dressing or first coat
13.2mm
100% passing 22.4mm sieve and retained on 11.2mm sieve
Second coat of 2 coat
9.5mm
100% passing 11.2mm sieve and retained on 5.6mm sieve
Table 500 – 10, Binder rates and chipping quantities Chipping size
Bitumen kg/m2
Emulsion kg/m2 Chips cum/m2
13.2
1.0
1.5
0.010
9.5
0.9
1.4
0.008
6.3
0.75
1.1
0.004
Appropriate technology and machinery for Surface Dressing 1. Applying Prime Coat : Hand-held lance with sprayer operated by Compressor 2.Heating Bitumen : Bitumen Boiler of small capacity
3.Applying Binder : Hand-held lance with sprayer, operated by Compressor 4. Spreading stone chips : Agricultural tractor-towed Spreader Box 5. Rolling : 80-100 kN smooth-wheeled roller
Surface dressing using 0.04 cum of 6.3 mm chips over a coat of 7.5 Kgs of bituminous material on a WBM surface laid without any gravelly soil. It not only prevents the WBM surface from raveling for a few days but also facilitate efficient laying of BT surfacing at the appropriate time
MORD 508 Open Graded Pre Mix Carpet (OGPC) 20 mm thick pre mix carpet Aggregate 13.2mmchips = 0.18cum 11.2mm chips = 0.09cum (13.2mm = passing 22.4 & retained on 11.2mm sieves 11.2mm chips passing 13.2mm retained on 5.6mm sieves) Binder Bitumen @ 14.6 kg/ 10sqm Emulsion @ 21.5 kg/ 10sqm AIV < 40%, FIV < 25% and WA < 1% for coarse aggregates.
Appropriate technology and machinery for Premix Carpet 1.Applying Prime Coat : Hand-held lance provided with sprayer, operated by compressor 2.Applying Tack Coat : Hand-held lance provided with sprayer, operated by compressor 3.Mixing of aggregates and bitumen in : Mini Hot Mix Plant, capacity of with specified quantities around 6 tonnes/hour 4.Transporting from the mixer to site : Tarpaulincovered tractor-trailer or hand barrows
Methodology for OGPC
1. Mixing should be thorough to ensure that a homogenous mixture is obtained. The temperature of bitumen at the time of mixing should be in the range of 150° C to 163° C and that of aggregates 155°C to 163°C, provided that the difference between the temperature of aggregate and the binder should not exceed 14°C. If modified bitumen is used, temperature should be as recommended in Subsection 512. The temperature at the time of discharge of the mixture should be between l30°C and 160°C. 2. The premixed material shall be spread on the road surface with rakes. 3. Commence rolling with 80-100 kN rollers (three-wheel or tandem type), beginning from the edge and progressing towards the centre longitudinally. (On super elevated portions, rolling should progress from lower to upper edge parallel to centre line of pavement). Continue rolling operations till a smooth uniform surface is achieved and all roller marks are eliminated. Each pass should have an overlap of at least one-third of the track made in the preceding pass. 4. Correct any high spots or depressions noticed after the roller has passed over the whole area once by removing or adding premixed material and recompacting. 5. Provide a seal coat to the surface immediately after laying the carpet as per details in Sub-section
DO’s 1. Ensure that the aggregates and binder satisfy the specified requirements.
Don’ts 1. Do not allow manual mixing.
2. Do not undertake work in 2. Before opening the bitumen foggy, rainy or windy emulsion drum, roll the drum weather or when the at slow speed, to and fro at minimum air temperature is least five times for a distance less than 10°C. of about 10 m to ensure proper distribution of storage 3. Do not allow any traffic sedimentation. unless the emulsion is properly set and the surface 3. As far as possible use has acquired adequate suitable cold mixing plant stability
MORD 510 Seal Coat Table 500-16, Requirement of materials fo seal coat Type of seal coat Type A Liquid seal coat
Per 10sqm Bitumen kg Emulsion kg 9.8 12 to 14
Type B Pre mix seal coat
6.8
10 to 12
Type C Pre mix seal coat using 6.7mm chips
4.5% by weight of total mixture
9 to 11
Quantity of chips per 10sqm 6.7mm chips (passing 100% on 11.2mm sieve and fully retained on2.36mm sieve) for type A Sand or grit (for type B) passing 2.36mm sieve and retained on 180 micron sieve 6.7mm (passing 100% on 9.5mm sieve and fully retained on2.36mm sieve) for type C
0.09cum 0.06cum 0.09cum
MORD 509 Mix Seal Surfacing Table 500-15, Aggregate Gradation IS Sieve designation mm
13.2 11.2 5.6 2.8 0.09
Cumulative % by weight of total aggregate passing Type A Type B
100 52 – 88 14 – 38 0-5
100 88 – 100 31 – 52 5 – 25 0-5
Chips @ 0.27cum per 10sqm Binder @ 22kg for type A and 19kg for type B
Mix Seal Surfacing 20mm thick over WMM treated with single coat surface dressing with 0.04 cum of 6.3mm chips over 7.5kg/10sq.m bituminous coat (SSD).
Mix Seal Surfacing 20mm thick over WMM treated with SSD. SSD is preferred to prime coat as we have to allow traffic.
Revendrapadu Sitanagaram runs along Buckingham canal for 4km and it was in a very bad shape with lot of pot holes and sunken portions. Number of renewals were done but the road condition remained the same.
There is lot of WBM crust with gravel blindage. The road was fully picked up, gravel and BT pieces removed to possible extent, sectioned, rolled, stone dust blindage done and rolled.
Condition of Nidubrolu Chandolu road. Soaked and softened gravel in gravel base and blindage in WBM is the cause for this condition.
Condition of Nidubrolu Chandolu road after full picking, removing gravel to possible extent, sectioning metal, rolling and dust blindage.
Condition of Nidubrolu Chandolu road after doing single coat surface dressing
Chandolu bridge to Nijampatnam road runs on high bank of irrigation canal. Doing BT patch work for BT renewal is very difficult. It is proposed to recycle the WBM crust.
Condition of Chandolu bridge to Nijampatnam road after full picking, removing gravel to possible extent, sectioning metal, rolling and dust blindage.
Chandolu bridge to Nijampatnam road after single coat surfacing over recycled surface.
Chandolu bridge to Nijampatnam road after doing BM + SDBC. Shoulder work to be done.
Repalle Tummala Gangadapalem road after picking, sectioning, stone dust blindage, rolling and single coat surface dressing
Repalle Tummala Gangadapalem road after completion BM and SDBC
Gravel collected for berms sticking to the BT wearing coat and part of the fines of gravel permeate into it. While cleaning the gravel BT layer is getting peeled off.
Berms done with selected earth on Rajupalem Bodhanam road
WBM over gravel base
Widening the formation to the required width
Both sides shouders are cut to a depth to get the required formation width at top. Selected earth with a minimum density of 1.75g/cc in layers and compacted at OMC.
Formation of top is completed and repairs to carriageway will be taken up.
After the resurfacing is completed.
