CONTENTS
1. Introduction
2. Clearing and Grubbing
3. Earthworks
4. Granular Sub Base Course
5. Wet Mix Macadam
6. Prime Coat
7. Tack Coat
8. Bituminous Macadam
9. Dense Bituminous Macadam
10. Bituminous Concrete (Wearing Course)
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1. INTRODUCTION
1.1 SCOPE
This document outlines the procedure for the method of construction of major items of Road works true to the lines, grades, shapes and cross sections as per approved drawings and specifications of the Project.
The Standard Specifications for Road and Bridge Works of Ministry of Shipping, Road Transport & Highway (MoSRTH) shall be consulted for the details which are not covered in this document.
1.2 FIELD OF APPLICATION
1. Clearing and Grubbing
2. Earthworks
3. Granular Sub Base Course
4. Wet Mix Macadam
5. Prime Coat
6. Tack Coat
7. Bituminous Macadam
8. Dense Bituminous Macadam
9. Bituminous Concrete (Wearing Course)
1.3. REFERENCES
1. Concessionaire Agreement
2. MoSRTH Specifications for Road and Bridge Works
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2. CLEARING AND GRUBBING
2.1 OBJECTIVE:
To out line the procedure for method of construction of Clearing and Grubbing to the required dimensions and levels conforming to approved drawings and project specifications.
2.2 CONSTRUCTION EQUIPMENT:
• Bull Dozer
• Excavator
• Motor Grader
• Soil Compactor
• Wheel Loader
• Water Tanker
• Dump Trucks
2.3 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for Clearing and Grubbing work:
a The original ground level at every 20m interval longitudinally and 3m transversely and also at CL, edge of shoulder and toe of the existing road shall be recorded. In widely varying terrain and in sharp curve portions the longitudinal spacing may be reduced to 10m.
b The toe width with respect to finish road level shall be calculated & marked it on the ground with an additional margin on both sides of carriageway.
c The centerline of proposed road shall be marked from the given reference point on ground with pegs.
d Grubbing, uprooting of vegetation, grass, bushes, shrubs, top organic soil not exceeding 150mm in thickness (201.1), rubbish, etc. shall be cleared and removed with the help of dozer, grader & excavator.
e All trees, stumps, etc., falling within excavation and fill lines shall be cut to such depth below ground level that in no case these fall within 500 mm of Subgrade. All branches of trees extending above proposed roadway shall be trimmed.
f All excavations below the general ground level arising out of the removal of trees, stumps, etc., shall be filled with suitable material and compacted thoroughly so as to make the surface at these points conform to the surrounding area.
g Minor undulations and pits shall be cut and filled to obtain clean & clear bed matching to the road profile.
h The moisture content of each layer of soil at the time of compaction shall be from +1% to –2% of optimum moisture content. (305.3.5.2)
i Watering and rolling shall be carried out for bed / foundation layer with vibratory roller having 80 - 100 KN static weight (305.3.6) to achieve 95% relative compaction with respect to laboratory dry density found as per Modified Proctor Method (Table:300-2). In case of pits or uneven ground surface where compaction can not be done with vibratory roller, mini tandem rollers or tamping compactors shall be used.
j The compaction control of bed shall be exercised as per Sub section 903.2.2 of MoSRTH Specifications.
k After compaction of the bed, the levels at an interval as mentioned at para (a) above shall be taken before placing of embankment/Subgrade layer.
l All materials arising from clearing & grubbing operations shall be disposed of by the Concessionaire as per Concession Agreement or as directed by the Engineer.
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3. EARTH WORKS
3.1 OBJECTIVE:
To out line the procedure for method of construction of Embankments, Subgrades, Earthen Shoulders and Miscellaneous Backfills to the required lines, grades and cross sections conforming to approved drawings and project specifications.
3.2 CONSTRUCTION EQUIPMENT:
• Bull Dozer
• Excavators
• Motor Graders
• Soil Compactors
• Wheel Loader
• Water Tankers
• Dump Trucks
3.3 MATERIAL:
The materials used in embankments shall be soil, moorum, gravel, a mixture of these or any other material approved by the engineer. These materials shall be free of logs, stumps, roots, rubbish or any other ingredient likely to deteriorate or affect the stability of the embankment.
The maximum laboratory density of material used for embankments up to 3 m height and not subjected to extensive flooding shall not be less than 15.2 K.N/cu.m; and for embankments exceeding 3 m height or embankments of any height subject to long periods of inundation shall not be less than 16.0 K.N/cu.m; and for subgrade and earthen shoulders / verges / backfilling shall not be less than 17.5 KN/cu.m. It shall be ensured prior to actual execution that the material to be used in the subgrade satisfies the requirements of design CBR of 10.
The size of the coarse material in the mixture of earth shall ordinarily not exceed 75 mm when being placed in embankment and 50 mm when placed in the subgrade.
3.4 SOURCE APPROVAL:
Suitable borrow areas shall be identified and samples taken from borrow areas shall be tested for its suitability in Embankments / Sub-grade construction as per specification requirements.
3.5 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for construction of earth works:
a After the site has been cleared the limits of embankment shall be marked by fixing pegs on both sides at regular interval as guides before commencing the earthwork.
b The embankment / subgrade shall be built sufficiently wider than the design dimension so that surplus material may be trimmed, ensuring that the remaining material is to the desired density and in position specified and conforms to specified side slopes.
c If the foundation of the embankment is in an area with stagnant water the same shall be removed by bailing out or pumping and the area of the embankment foundation shall be kept dry. Where embankment / backfilling is to be placed under water, only acceptable granular material or rock shall be used.
d Original ground, where necessary, shall be leveled to facilitate placement of first layer of embankment, scarified, mixed with water and then compacted by rolling so as to achieve minimum dry density as per specification i.e. 95% of Lab MDD and 97% of Lab MDD in case of Sub-grade.
e If the difference between the subgrade top level and ground level, in case, is less than 0.5 m and the ground does not have 97% relative compaction with respect to Lab MDD, the ground shall be loosened up to a level 0.5 m below the subgrade level, watered and compacted in layers to not less than 97% of Lab MDD.
f The embankment / Sub-grade material shall be spread in layers of uniform thickness not exceeding 200 mm compacted thickness over the entire width of embankment by mechanical means, finished by motor grader having hydraulic control to achieve specific slope and grade and compacted to achieve required density. Successive layers shall not be placed until layer under construction has been thoroughly compacted to specified requirement and approved by engineer.
g Where the embankment is to be placed over an existing road surface, the work shall be carried out as per Sub Section 305.4.3 of MoSRTH Specifications.
h When the existing embankment and/or subgrade is to be widened and its slopes are steeper than 1 vertical on 4 horizontal, continuous horizontal benches, each at least 300 mm wide, shall be cut into the old slope for ensuring adequate bond with the fresh embankment/subgrade material to be added. The material obtained from cutting of benches shall be utilized in the widening of the embankment/subgrade.
i When the existing slope against which the fresh material is to be placed is flatter than 1 vertical on 4 horizontal, the slope surface may only be ploughed or scarified instead of resorting to benching.
j Moisture content of the soil shall be measured by moisture meter before taking up compaction of each layer as per IS 2720 (Part-2). If the moisture content is less than the designed OMC plus due allowance for evaporation losses as per IS 2720 (Part-2), water shall be sprinkled from a water tanker fitted with c controllable rate of flow to variable widths of surface uniformly without any flooding. After adding required amount of water, the soil shall be processed by means of graders, harrows, rotary mixture or any other method in practice until the layer is uniformly wet.
k The compaction shall be done with the help of vibratory roller of 80-100 KN static weight with plain or pad foot drum or heavy PTR of adequate capacity capable of achieving required compaction.
l Where the width of the widened portion is insufficient to permit the use of conventional rollers, compaction shall be carried out with the help of small vibratory rollers/plate compactors/power rammers or any other appropriate equipment.
m The measurement of field dry density of each compacted layer my be done either by a nuclear moisture / density meter calibrated to provide test results identical to that obtained in accordance with IS 2720 (Part-28) or by sand replacement method as per IS 2720 (Part-28).
n Subsequent layer shall be placed only after the finished layer has been tested and accepted by the Engineer.
o When the embankment / subgrade reaches top position, finishing operations like the work of shaping and dressing the shoulders/verge/roadbed and side slopes shall be done to conform to the alignment, levels, cross sections and dimensions shown on the drawings subjected to the surface tolerance as per Sub Section 902 of MoSRTH Specifications.
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4. GRANULAR SUB-BASE
4.1 OBJECTIVE:
To out line the procedure for the method of construction of Granular Sub-base on prepared subgrade to the required lines, grades and cross sections conforming to approved drawings and project specifications.
4.2 CONSTRUCTION EQUIPMENT:
• Motor Graders
• Soil Compactors
• Water Tankers
• Dump Trucks
4.3 MATERIAL:
The material to be used for the work shall be natural sand, moorum, gravel, crushed stone or combination there of depending upon the grading requirements. Materials like crushed slag, crushed concrete, brick metal and kankar shall be allowed to use only with the specific approval of the engineer. The material shall be free from organic or other deleterious constituents and conform to Grading-I of Table 400-1 of MoSRTH Specifications.
Table 400-1 Grading-I for Close Graded Granular Sub base Materials
IS sieve Designation Percent by weight passing the IS sieve
GRADE-I
75 mm 100
53 mm 80-100
26.5 mm 55-90
9.5 mm 35-65
4.75 mm 25-55
2.36 mm 20-40
425 micron 10-25
75 micron 3-10
Physical Requirements:
• The water absorption value of the coarse aggregate shall be determined as per (IS-2386 Part-3). If this value is grater than 2% then soundness test shall be carried out on the material.
• Minimum CBR value for the GSB material for Grade-I is 30%.
• The material passing through 425 micron sieve of GSB material when tested in accordance with IS 2720 part-5 shall have liquid limit and Plasticity Index not more than 25% and 6% respectively.
4.4 SOURCE APPROVAL:
Suitable borrow areas shall be identified and samples taken from borrow areas shall be tested for its suitability in Granular Sub-base construction as per specification requirements.
4.5 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for construction of GSB works:
a Immediately prior to laying of GSB material for Sub-base, the subgrade already finished shall be prepared by removing all vegetation and other extraneous matter, lightly sprinkled with water if necessary and rolled with two passes of 80-100 KN smooth wheeled roller.
b The GSB material of Grading-I shall be spread on the prepare surface of subgrade with the help of a motor grader to the required slope and grade.
c Moisture content of loose material shall be checked in accordance with IS:2720 (Part 2) and suitably adjusted by sprinkling additional water from truck mounted water tank uniformly and at controlled quantities to variable widths of surface so that at the time of compaction it is +1% to -2% below the optimum moisture content.
d After water has been added, the material shall be processed by mechanical or other approved means like disc harrows, rotavators until the layer is uniformly wet.
e Immediately after fulfillment of moisture content requirements, rolling shall be started. If the thickness of the compacted layer does not exceed 100 mm a smooth wheeled roller of 80 to 100 KN weight may be used. For a compacted single layer up to 225mm thickness, the compaction shall be done with the help of a vibratory roller of minimum 80 to 100 KN static weight with plain drum of pad foot-drum or heavy pneumatic roller capable of achieving the required compaction. Each pass of the roller shall uniformly overlap not less than the one third of the track made in the preceding pass. The speed of the roller shall not be exceeded 5KM per hour.
f Rolling shall be commenced at lower edge and proceed towards the upper edge longitudinally for portions having unidirectional cross fall and super elevation and shall commence at the edges and progress towards the centre for portions having cross fall on both sides.
g Rolling shall be continued till the density achieved is at least 98% of the maximum dry density for the material determined as per IS:2720 (Part 8).
h All loose, segregated or otherwise defective areas shall be made good to the full thickness of layer and re-compacted.
i All works performed shall be verified to confirm to lines, grades, cross sections and dimensions shown on drawings subject to the permitted tolerance as per Sub Section 902 of MoSRTH Specifications.
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5. WET MIX MACADAM BASE COURSE
5.1 OBJECTIVE:
To out line the procedure for the method of construction of Wet Mix Macadam Base Course on prepared Granular sub-base to the required lines, grades and cross sections conforming to approved drawings and project specifications.
5.2 CONSTRUCTION EQUIPMENT:
• Aggregate Mixing Plant with all assembly
• Mechanical Paver
• Vibratory Rollers
• Water Tankers
• Dump Trucks
5.3 MATERIAL:
• Material intended to use in the construction of WMM are crushed stone aggregates of sizes 53 mm to 6 mm (All-in-aggregate), 20mm, 10 mm, Crusher dust & sand
• The Coarse aggregates shall be conformed to the physical requirement given in table below:
Sl. No. TEST TEST MATERIAL REQUIREMENT
1 *Los Angeles abrasion value or
Aggregate impact value IS 2386 ( Part-IV)
IS 2386 ( Part-IV) or IS: 5640 40% (max)
30% (max)
2 Combined flakiness and Elongation indices (total) IS 2386 (Part-I) 30% (max)
*Aggregate may satisfy requirement of either of the two tests.
• The aggregates shall be conformed to the grading given as below:
IS Sieve Designation % by wt. Passing the IS : sieve
53.0mm 100
45.0 mm 95-100
26.5 mm -
22.40 mm 60-80
11.20 mm 40-60
4.75 mm 25-40
2.36 mm 15-30
600.0 micron 8-22
75.0 micron 0-8
• Materials finer than 425 micron shall have Plasticity Index not exceeding 6.
• The final Gradation approved within the above limits shall be well graded from Coarse to fine and shall not vary from these limits on the sieve to high limits on adjacent sieve or vice versa.
• If the water absorption value of coarse aggregate is greater than 2%, Soundness test shall be done.
• Control on the quality of materials shall be exercised in accordance with Section 900 of MoSRTH Specifications.
5.4 PREPARATION OF WMM MIX:
Preparation of the mix shall be carried out in approved calibrated aggregate mixing plant of suitable capacity having provision for controlled addition of water and forced / positive mixing arrangement like pug mill.
Before preparation of the mix in the pug mill the material shall be filled in four bins as mentioned below.
Bin No-1 All-in-Aggregate
Bin No-2 All-in-Aggregate
Bin No-3 20 mm + 10 mm (Premixed separately in the required ratio)
Bin No-4 Sand & Crusher dust (Premixed separately in the required ratio)
Incase 40 mm aggregate is available the same can be filled in Bin No – 1 & 2
After placing the material in the above manner the mix shall be prepared by adding the required water as per the job mix formula. While adding water, due allowance shall be made for evaporation losses. However, at the time of compaction, water in Wet Mix Macadam should not vary from the optimum value by more than agreed limits. The mixed material should be uniformly wet and no segregation should be permitted.
5.5 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for construction of WMM works:
a The surface of the base to receive the Wet Mix Macadam course shall be prepared to the specified lines and cross fall (camber) and made free from dust and other extraneous material.
b While constructing Wet Mix Macadam, arrangement shall be made for the lateral confinement of Wet Mix. This shall be done by lying materials in adjoining shoulders along with that of Wet Mix Macadam layer.
c Immediately after mixing, the aggregate shall be spread uniformly and evenly upon the prepared sub-base in required quantities. In no case should these be dumped in heaps directly on the area where these are to be laid nor shall their hauling over a partly completed stretch be permitted.
d The mix shall be spread either by a paver finisher or motor grader. However, in restricted locations and in narrow widths where the paver can not be operated, the manual spreading shall be done. The material shall be spread uniformly all over the surface. The surface of aggregate shall be carefully checked with templates and all high or low spots remedied by removing or adding aggregate as may be required.
e The layer may be tested by depth blocks during construction. No segregation of layer and fine particles shall be allowed. The aggregates as spread shall be of uniform gradation with no pockets of fine materials.
f After the mix has been laid to the required thickness, grade and crossfall / camber the same shall be uniformly compacted to the full depth with suitable roller.
g If the single compacted layer thickness does not exceed 100mm, the compaction may be done with the help of smooth wheel roller of 80 to 100 KN weight. For a compacted single layer upto 200 mm, the compaction shall be done with the help of vibratory roller of minimum static weight of 80 to 100 KN or equivalent capacity roller. The speed of roller shall not exceed 5 Km/hour.
h In portions having unidirectional cross-fall/ super elevation, rolling shall commence from the lower edge and progress gradually towards the upper edge. There after roller should progress parallel to the center line of the road, uniformly overlapping each preceding track by at least one-third width until the entire surface has been rolled.
i In portion in camber, rolling should begin at the edge with the roller running forward and backward until the edges have been firmly compacted. The roller shall then progress gradually towards the center parallel to the centerline of the road, uniformly overlapping each preceding track by at least one-third width until the entire surface has been rolled. Any displacement occurring as a result of reversing of the direction of the roller or from any other cause shall be corrected at once as specified and / or removed and made good.
j Along forms, Kerbs, walls or other places not accessible to the roller, the mixer shall be thoroughly compacted with mechanical tamper or a plate compactor. Skin patching of an area without scarifying the surface to permit proper bonding of the added material shall not be permitted.
k Rolling should not be done when the sub-base is soft or yielding or when it causes a wave like motion in the sub-base. If irregularities develop during rolling which exceed 12mm when tested with a 3mtr straight edge, the surface should be loosened and premixed material added or removed as required before rolling again so as to achieve a uniform surface conforming to the desired grade and cross-fall. Rolling shall be continued till the density achieved is at least 98% of the maximum dry density for the material as determined by the method outlined in IS:2720 (Part 8).
l After completion, the surface of any finished layer shall be well closed, free from movement under compaction equipment or any compaction planes, ridges, cracks and loose material. The finished layer shall be prevented from the movement of vehicles etc. by placing medium size stones to discourage traffic entry. All Care shall be taken to prevent the contamination of laid W.M.M. with foreign unwanted soil, dust, etc.
m All loose, segregated or otherwise defective areas shall be made good to the full thickness of the layer and recompacted.
n After final compaction of Wet Mix Macadam course, the road shall be allowed to dry for 24 hours.
o The control on the quality of works shall be exercised in accordance with Section 900 of MoSRTH Specifications. The levels of the finished WMM layer shall not vary beyond the tolerances of ± 10mm from those calculated with reference to the longitudinal and cross-profile of the road shown on the drawings.
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6. PRIME COAT
6.1 OBJECTIVE:
To out line the procedure for the method of construction of laying Prime Coat on prepared Wet Mix Macadam base to the required lines conforming to approved drawings and project specifications.
6.2 CONSTRUCTION EQUIPMENT:
• Bitumen Distributor with self-propelled or towed bitumen pressure sprayer
• Hand Sprayers
• Mechanical Broom
• Air Compressor
6.3 MATERIAL:
• Since WMM is considered to be material of low porosity, it is proposed to use Slow Setting Emulsion for Prime Coat. The Slow Setting Emulsion shall comply with IS:8887 and shall be procured from reputed manufacturers.
• Test Certificates shall be obtained from Manufacturer for the material supplied and the same shall be submitted to IC.
• The quantity of bituminous primer to be sprayed per 10 Sq.m shall be kept at 7.5 Kg. The spray rate shall be maintained between limits 6 to 9 Kg per 10 Sq.m.
6.4 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for laying of Prime Coat:
a Prior to applying primer on prepared WMM surface, the surface shall be carefully swept clean of dust and loose particles by mechanical broom and air compressor with proper care not to disturb the interlocked aggregate. To achieve this, the WMM surface layer, if required, shall be lightly sprayed with water and surface is allowed to dry to a stage where the surface is slightly moist but no free or standing water shall be present at the time of priming.
b The primer shall not be applied to a wet surface or during a dust storm or when the weather is foggy, rainy or windy or when the temperature in the shade is less than 10° C.
c The bituminous primer shall be sprayed uniformly with bitumen distributor at specified speed. The speed of bitumen distributor shall be so regulated so as to achieve the required rate of spray within tolerance limits. The spray test shall be conducted to check the bitumen spray rate per unit area.
d Where the areas are inaccessible to the distributor or in narrow strips, hand sprayers shall be used for spraying of primer.
e The primed surface shall be cured for 24 hours or such other period as is found necessary to allow all the volatiles to evaporate before any subsequent surface treatment or mix is laid. Any unabsorbed primer shall first be blotted with an application of sand, using the minimum quantity possible. A primed surface shall not be opened to traffic other than that necessary to lay the next course. A very thin layer of clean sand shall be applied to the surface of the primer, to prevent the primer picking up under the wheels of the paver and the trucks delivering bituminous material to the paver.
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7. TACK COAT
7.1 OBJECTIVE:
To out line the procedure for the method of construction of Tack Coat application over primed surface / existing bituminous road surface (preparatory to the superimposition of a bituminous mix) to the required lines conforming to approved drawings and project specifications.
7.2 CONSTRUCTION EQUIPMENT:
• Bitumen Distributor with self-propelled or towed bitumen pressure sprayer
• Hand Sprayers
• Mechanical Broom
• Air Compressor
7.3 MATERIAL:
• The material used for tack coat shall be Rapid Setting Emulsion complying to IS:8887 and shall be procured from reputed manufacturers.
• Test Certificates shall be obtained from Manufacturer for the material supplied and the same shall be submitted to IC.
• The quantity of R.S. Emulsion to be sprayed per 10 Sq.m shall be kept at 2.75 Kg for surfaces treated with primer and at 2.25 Kg for existing bituminous road surface preparatory to the superimposition of a bituminous mix. The spray rate shall be maintained between the limits as specified in the Section 503 of MoSRTH Specifications.
7.4 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for application of Tack Coat:
a The surface on which the tack coat is to be applied shall be made clean and free from dust, dirt and any extraneous by mechanical broom and/or air compressor with proper care not to disturb the interlocked aggregate.
b The tack coat shall not be applied to a wet surface or during a dust storm or when the weather is foggy, rainy or windy or when the temperature in the shade is less than 10° C.
c The bituminous emulsion shall be sprayed uniformly with bitumen distributor at specified speed. The speed of bitumen distributor shall be so regulated so as to achieve the required rate of spray within tolerance limits. The spray test shall be conducted to check the bitumen spray rate per unit area.
d Where the areas are inaccessible to the distributor or in narrow strips, hand sprayers shall be used for application of tack coat.
e Tack coat may not be applied over a freshly laid bituminous layer, which has not been subjected to traffic or contaminated by dust, where the overlay is completed within two days.
f The tack coat shall be left to cure for 2 to 4 hours whichever is found necessary to allow all the volatiles to evaporate before any subsequent construction is started.
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8. BITUMINOUS MACADAM
8.1 OBJECTIVE:
To out line the procedure for the method of construction of Bituminous Macadam in one or more layers (the thickness of single layer shall be 50 mm to 100 mm) to the required lines, grades and cross sections conforming to approved drawings and project specifications.
8.2 CONSTRUCTION EQUIPMENT:
• Hot Mix Plant of adequate capacity
• Dump Trucks
• Sensor Pave
• Power Broom / Air Compressor
• Self- propelled or towed bitumen pressure sprayer.
• Vibratory Tandem Rollers
• Pneumatic Tyred Rollers
• Steel pegs & thin wire.
8.3 MATERIAL:
The following materials shall be used.
Bitumen: The bitumen shall be paving bitumen of penetration grade complying with IS Specifications for “Paving Bitumen” IS:73 and the penetration grade shall be as specified in the Concession Agreement.
Coarse Aggregate: The coarse aggregates shall be of crushed rock, crushed gravel or other hard material and shall be clean, hard, durable, free from dust or soft or friable matter, organic or other deleterious substances. The aggregates shall satisfy the physical requirements as given in the Table – 8.1.
The aggregate may satisfy the strength requirements of either Los Angeles Abrasion Value or Aggregate Impact Value. The water sensitivity test is only required if the minimum retained coating in the stripping test is less than 95%.
Fine Aggregate: Fine aggregate shall be the fraction passing 2.36 mm sieve and retained on 75 micron sieve, consisting of crusher run stone aggregate or screening sand, or a mixture of both. Fine aggregate shall be clean, hard, durable, dry and free from dust, and soft or friable matter, organic or other deleterious substances.
Filler: Filler shall consist of finely divided mineral matter such as stone dust. The filler shall be free from organic impurities and have a plasticity Index not greater than 4.
Aggregate Gradation: The combined coarse, fine aggregate and filler (when used) shall produce a well-graded mixture and the grading shall fall within the limits given in Table – 8.2 with respect to type and quantity of bitumen and appropriate thickness.
Table – 8.1: Physical Requirements for Coarse Aggregates
Property Test Reference: Specification
Cleanliness (Dust) Grain Size Analysis IS 2386 - Part-1 Max 5% passing 0.075mm sieve
Particle Shape Flakiness and Elongation Index IS 2386 - Part-1 30% max.
Strength 1. Los Angeles Abrasion Value
2. Aggregate Impact Value IS 2386 Part-4
IS 2386 Part-4 Max 40%
Max 30%
Durability Soundness:
1. Sodium Sulphate
2. Magnesium Sulphate
IS 2386 Part-5
IS 2386 Part-5
12% max.
18% max
Water Absorption Water absorption IS 2386 Part-3 2% max
Stripping Coating and Stripping of Bitumen Aggregate Mixer IS 6241 Minimum retained Coating 95 %
Water Sensitivity Retained Tensile Strength AASHTO T283 Min 80%
Table – 8.2: Combined Aggregate Gradation for Bituminous Macadam
Grading 1 2
Nominal Aggregate Size 40 mm 19 mm
Layer Thickness 80-100 mm 50-75 mm
IS Sieve (MM) Cumulative % by weight of total aggregate passing
45 100
37.5 90-100
26.5 75-100 100
19 - 90-100
13.2 35-61 56-88
4.75 13-22 16-36
2.36 4-19 4-19
0.3 2-10 2-10
0.075 0-8 0-8
Bitumen Content % by mass of total Mix 3.1 – 3.4 3.3 – 3.5
Bitumen Grade (pen) 35 or 90 35 or 90
8.4 LAYING TRIALS:
The laying trials shall be carried out on a suitable area to demonstrate that the proposed mix can successfully be laid and compacted in accordance with project specifications. During these trials, the plant and laying/compaction equipment shall be established to produce satisfactory results.
The density of the finished paving layer shall be determined by taking cores after 24 hours of laying. The construction of permanent works shall be taken up after successful site trial satisfying the job mix formula and Project Specifications.
8.5 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for the construction of Bituminous Macadam:
a Bituminous Macadam mix shall be prepared in a Batch Type Hot Mix Plant. The temperature of binder at the time of mixing shall be in the range of 150° C – 165° C and that of the aggregate shall be in the range of 150° C – 170° C. It shall be ensured that the difference in temperature between the binder and aggregate at no time exceeds 14° C. Mixing shall be thoroughly done to ensure that a homogenous mixture is obtained in which all particles of the aggregates are coated uniformly and the discharge temperature of mix shall be between 140° C to 165° C. The mixture shall be transported from the mixing plant to the point of use in suitable tipper vehicles. The vehicles employed for transport shall be clean and be covered in transit. A thin coating of diesel or lubricating oil may be applied to the interior of the vehicle to prevent sticking and to facilitate discharge of the material.
b The surface on which the BM mix is to be laid shall be cleaned of all loose and extraneous matter by means of mechanical broom or air compressor and tack coat shall be applied.
c The work of lying shall not be taken up during rainy or foggy weather or when the base course is damp or wet, or during dust storm or when the atmospheric temperature in shade is less than 10° C.
d The mix transported from the hot mix plant to the site shall be spread by means of self–propelled sensor paver with suitable screeds capable of spreading, tamping and finishing the mix to specified grade, lines and cross-section. The temperature of mix at the time of lying shall be in the range of 120° C - 160° C. Mixes with a temperature less than 120° C shall not be put into the paver spreader. Before the lane is compacted, the material along the unsupported edges should be butted and slightly elevated with tamping tool. This sets up the edges and permits the full weight of roller to bear on the extreme edge of mat.
e Longitudinal joints and edges shall be constructed true to delineating line parallel to the centre line of road. Longitudinal and Transverse joints shall be offset at least 250mm from those in lower course. All transverse joints shall be cut vertically to the full thickness of previously laid mix with asphalt cutter and surface painted with hot bitumen before placing fresh material. Cold longitudinal joints shall be properly heated with joint heater to attain temperature of 80° C before laying the adjacent material.
f After spreading the mix by paver, it shall be thoroughly compacted by rolling with a set of roller moving at speed not more than 5 km./hr. The initial or breakdown rolling shall be done with 80 – 100 KN static weight smooth wheeled roller. The intermediate rolling shall be done with a pneumatic roller of 150-250 KN weight having a type pressure of at least 0.7 MPa. The finishing rolling shall be done with 60 – 80KN weight smooth wheeled tandem roller. All the compaction operations, i.e. breakdown rolling and intermediate rolling can be accomplished by using vibratory tandem roller of 80 – 100KN static weight.
g The wheels of roller shall be kept moist to prevent the mix from adhering to them. Rolling shall be done longitudinally. The roller shall first compact material adjacent to joints and then work from lower to the upper side of the layer, overlapping on successive passes by at least one-third of the width of the rear roll or, in the case of PTR, at least the normal width of 300 mm. In portions with super-elevated and uni-directional camber, after the edge has been rolled, the roller shall progress from the lower to the upper edge.
h Rolling shall be continued till the density achieved is at least 97% of the laboratory Marshall Specimen or there is no further movement under the roller. Rolling operations shall be completed in all respects before the temperature of the mix falls below 100° C.
i In areas with restricted space where sensor paver can not be used, the material shall be spread, raked and leveled with suitable hand tools and compacted.
j Density of compacted layer shall be checked by core cutting method at the rate of one test for density per 250sq.m.area for the confirmation of achieved density as per the requirements.
k The surface finish of the completed construction shall conform to the requirements of Section 902 of MoSRTH Specifications.
l The newly laid surface shall not be open to traffic for at least 24 hrs after laying and completion of compaction.
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9. DENSE BITUMINOUS MACADAM
9.1 OBJECTIVE:
To out line the procedure for the method of construction of Dense Bituminous Macadam in one or more layers (the thickness of single layer shall be 50 mm to 100 mm) to the required lines, grades and cross sections conforming to approved drawings and project specifications.
9.2 CONSTRUCTION EQUIPMENT:
• Hot Mix Plant of adequate capacity
• Dump Trucks
• Sensor Pave
• Power Broom / Air Compressor
• Self- propelled or towed bitumen pressure sprayer.
• Vibratory Tandem Rollers
• Pneumatic Tyred Rollers
• Steel pegs & thin wire.
9.3 MATERIAL:
The following materials shall be used.
Bitumen: The bitumen shall be paving bitumen of penetration grade complying with IS Specifications for “Paving Bitumen” IS:73 and the penetration grade shall be as specified in the Concession Agreement.
Coarse Aggregate: The coarse aggregates shall be of crushed rock, crushed gravel or other hard material and shall be clean, hard, durable, free from dust or soft or friable matter, organic or other deleterious substances. The aggregates shall satisfy the physical requirements as given in the Table – 9.1.
The aggregate may satisfy the strength requirements of either Los Angeles Abrasion Value or Aggregate Impact Value. The water sensitivity test is only required if the minimum retained coating in the stripping test is less than 95%.
Fine Aggregate: Fine aggregate shall be the fraction passing 2.36 mm sieve and retained on 75 micron sieve, consisting of crusher run stone aggregate or screening sand, or a mixture of both. Fine aggregate shall be clean, hard, durable, dry and free from dust, and soft or friable matter, organic or other deleterious substances. The plasticity Index of the fraction passing the 425-micron sieve shall not exceed 4 when tested in accordance with IS:2720 (Part-5).
Filler: Filler shall consist of finely divided mineral matter such as stone dust. The filler shall be free from organic impurities and have a plasticity Index not greater than 4.
Aggregate Gradation: The combined coarse, fine aggregate and filler (when used) shall produce a well-graded mixture and the grading shall fall within the limits given in Table – 9.2 with respect to type and quantity of bitumen and appropriate thickness.
Table – 9.1: Physical Requirements for Coarse Aggregates
Property Test Reference: Specification
Cleanliness (Dust) Grain Size Analysis IS 2386 - Part-1 Max 5% passing 0.075mm sieve
Particle Shape Flakiness and Elongation Index IS 2386 - Part-1 30% max.
Strength 1. Los Angeles Abrasion Value
2. Aggregate Impact Value IS 2386 Part-4
IS 2386 Part-4 Max 35%
Max 27%
Durability Soundness:
1. Sodium Sulphate
2. Magnesium Sulphate
IS 2386 Part-5
IS 2386 Part-5
12% max.
18% max
Water Absorption Water absorption IS 2386 Part-3 2% max
Stripping Coating and Stripping of Bitumen Aggregate Mixer IS 6241 Minimum retained Coating 95 %
Water Sensitivity Retained Tensile Strength AASHTO T283 Min 80%
Table – 9.2: Combined Aggregate Gradation for Dense Bituminous Macadam
Grading 1 2
Nominal Aggregate Size 40 mm 25 mm
Layer Thickness 80-100 mm 50-75 mm
IS Sieve (MM) Cumulative % by weight of total aggregate passing
45 100
37.5 95-100 100
26.5 63-93 90-100
19 - 71-95
13.2 55-75 56-80
9.5 - -
4.75 38-54 38-54
2.36 28-42 28-42
1.18 - -
0.6 - -
0.3 7-21 7-21
0.15 - -
0.075 2-8 2-8
Bitumen Content % by mass of total Mix Min 4.0 Min 4.5
Bitumen Grade (pen) 65 or 90 65 or 90
9.4 DESIGN MIX
Requirement of Mix: Apart from conformity with grading and quality requirements of individual ingredients, the mix shall meet the requirement of Marshall stability, Marshall flow (mm), Percent air voids, Minimum voids in mixed aggregates, Percent voids in mineral aggregates filled by bitumen, Binder percent by weight of total mix given in the following Table – 9.3:
Table – 9.3: Dense Bituminous Macadam Mix Requirements
1 Marshall Stability (ASTM Designation-D-1559) on Marshall Specimens Compacted by 75 Compaction blows on each end. 9.0 KN
2 Marshal flow 2 – 4
3 Percent air voids 3 - 6
4 Percent minimum voids in mineral aggregate 10 - 12
5 Percent voids in minerals aggregates filled with bitumen 65 – 75
6 Binders content percent by mass of total mix Not less than 4.0%
Binder Content: The binder content shall be optimized to achieve the requirements of the mix set out in above Table - 9.3
Job Mix Formula: The following details of Job Mix Formula shall be submitted:
• Source and location of all materials
• Proportions of all materials expressed as follows where each is applicable:
(a) Binder type, and percentage by weight of total mix;
(b) Course aggregate/fine aggregate/Mineral filler as percentage by weight of total aggregate including mineral filler.
• A single definite percentage passing each sieve for the mixed aggregate
• The individual grading of the individual aggregate fractions, and the portion of each in the combined grading
• The test results of Marshall Stability
• Test results of physical characteristics of aggregates to be used
• Mixing temperature and compacting temperatures.
Plant Trials - Permissible Variation from Job Mix Formula: After finalizing the job mix formula, plant trials shall be carried out to establish that the plant can be produced uniform mix conforming to the approved job mix formula. The permissible variations of the individual percentages of the various ingredients in the actual mix form the job mix formula to be used shall be within the limits as specified in the following Table – 9.4. These variations are intended to apply to individual specimens taken for quality control tests in accordance with Section 900 of MoSRTH Specifications.
Table – 9.4: Permissible Variations from the Job Mix Formula
Sl. No Description of Ingredients Permissible variation in %
1 Aggregate passing 19 mm sieve and larger + 8
2 Aggregate passing 13.2 mm , 9.5 mm + 7
3 Aggregate passing 4.75 mm + 6
4 Aggregate passing 2.36 mm, 1.18 mm, 0.6 mm + 5
5 Aggregate passing 0.3 mm, 0.15 mm + 4
6 Aggregate passing 0.075 mm + 2
7 Binder content + 0.3
8 Mixing temperature + 10° C
Laying Trials: After the plant trials have successfully completed, the laying trials shall then be carried out on a suitable area which may/may not be part of the works to demonstrate that the proposed mix can successfully be laid and compacted in accordance with project specifications. During these trials, the plant and laying/compaction equipment shall be established to produce satisfactory results.
The density of the finished paving layer shall be determined by taking cores after 24 hours of laying. The construction of permanent works shall be taken up after successful site trial satisfying the job mix formula and Project Specifications.
9.5 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for the construction of Dense Bituminous Macadam:
a Dense Bituminous Macadam mix shall then be prepared in a Batch Type Hot Mix Plant. The temperature of binder at the time of mixing shall be in the range of 150° C – 165° C and that of the aggregate shall be in the range of 150° C – 170° C. It shall be ensured that the difference in temperature between the binder and aggregate at no time exceeds 14° C. Mixing shall be thoroughly done to ensure that a homogenous mixture is obtained in which all particles of the aggregates are coated uniformly and the discharge temperature of mix shall be between 140° C to 165° C. The mixture shall be transported from the mixing plant to the point of use in suitable tipper vehicles. The vehicles employed for transport shall be clean and be covered in transit. A thin coating of diesel or lubricating oil may be applied to the interior of the vehicle to prevent sticking and to facilitate discharge of the material.
b The surface on which the DBM mix is to be laid shall be cleaned of all loose and extraneous matter by means of mechanical broom or air compressor and tack coat shall be applied.
c The work of laying shall not be taken up during rainy or foggy weather or when the base course is damp or wet, or during dust storm or when the atmospheric temperature in shade is less than 10° C.
d The mix transported from the hot mix plant to the site shall be spread by means of self–propelled sensor paver with suitable screeds capable of spreading, tamping and finishing the mix to specified grade, lines and cross-section. The temperature of mix at the time of lying shall be in the range of 125° C - 160° C. Mixes with a temperature less than 125° C shall not be put into the paver spreader. Before the lane is compacted, the material along the unsupported edges should be butted and slightly elevated with tamping tool. This sets up the edges and permits the full weight of roller to bear on the extreme edge of mat.
e Longitudinal joints and edges shall be constructed true to delineating line parallel to the centre line of road. Longitudinal and Transverse joints shall be offset at least 250mm from those in lower course. All transverse joints shall be cut vertically to the full thickness of previously laid mix with asphalt cutter and surface painted with hot bitumen before placing fresh material. Cold longitudinal joints shall be properly heated with joint heater to attain temperature of 80° C before laying the adjacent material.
f After spreading the mix by paver, it shall be thoroughly compacted by rolling with a set of roller moving at speed not more than 5 km./hr. The initial or breakdown rolling shall be done with 80 – 100 KN static weight smooth wheeled roller. The intermediate rolling shall be done with a pneumatic roller of 150-250 KN weight having a type pressure of at least 0.7 MPa. The finishing rolling shall be done with 60 – 80KN weight smooth wheeled tandem roller. All the compaction operations, i.e. breakdown rolling and intermediate rolling can be accomplished by using vibratory tandem roller of 80 – 100KN static weight.
g The wheels of roller shall be kept moist to prevent the mix from adhering to them. Rolling shall be done longitudinally. The roller shall first compact material adjacent to joints and then work from lower to the upper side of the layer, overlapping on successive passes by at least one-third of the width of the rear roll or, in the case of PTR, at least the normal width of 300 mm. In portions with super-elevated and uni-directional camber, after the edge has been rolled, the roller shall progress from the lower to the upper edge.
h Rolling shall be continuous till the density achieved is at least 98% of the laboratory Marshall Specimen. Rolling operations shall be completed in all respects before the temperature of the mix falls below 90° C.
i In areas with restricted space where sensor paver can not be used, the material shall be spread, raked and leveled with suitable hand tools and compacted.
j Density of compacted layer shall be checked by core cutting method at the rate of one test for density per 250sq.m.area for the confirmation of achieved density is at least 98% of that of Laboratory Marshall Specimen.
k The surface finish of the completed construction shall conform to the requirements of Section 902 of MoSRTH Specifications.
l The newly laid surface shall not be open to traffic for at least 24 hrs after laying and completion of compaction.
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10. BITUMINOUS CONCRETE
10.1 OBJECTIVE:
To out line the procedure for the method of construction of Bituminous Concrete for Wearing Course in one or more layers (the thickness of single layer shall be 25 mm to 100 mm) on a previously prepared bituminous bound surface to the required lines, grades and cross sections conforming to approved drawings and project specifications.
10.2 CONSTRUCTION EQUIPMENT:
• Hot Mix Plant of adequate capacity
• Dump Trucks
• Sensor Pave
• Power Broom / Air Compressor
• Self- propelled or towed bitumen pressure sprayer.
• Vibratory Tandem Rollers
• Pneumatic Tyred Rollers
• Steel pegs & thin wire.
10.3 MATERIAL:
The following materials shall be used.
Bitumen: The bitumen shall be paving bitumen of penetration grade complying with IS Specifications for “Paving Bitumen” IS:73 and the penetration grade shall be as specified in the Concession Agreement.
Coarse Aggregate: The coarse aggregates shall be of crushed rock, crushed gravel or other hard material and shall be clean, hard, durable, free from dust or soft or friable matter, organic or other deleterious substances. The aggregates shall satisfy the physical requirements as given in the Table – 10.1.
The aggregate may satisfy the strength requirements of either Los Angeles Abrasion Value or Aggregate Impact Value. The water sensitivity test is only required if the minimum retained coating in the stripping test is less than 95%.
Fine Aggregate: Fine aggregate shall be the fraction passing 2.36 mm sieve and retained on 75 micron sieve, consisting of crusher run stone aggregate or screening sand, or a mixture of both. Fine aggregate shall be clean, hard, durable, dry and free from dust, and soft or friable matter, organic or other deleterious substances. The plasticity Index of the fraction passing the 425-micron sieve shall not exceed 4 when tested in accordance with IS:2720 (Part-5).
Filler: Filler shall consist of finely divided mineral matter such as stone dust. The filler shall be free from organic impurities and have a plasticity Index not greater than 4.
Aggregate Gradation: The combined coarse, fine aggregate and filler (when used) shall produce a well-graded mixture and the grading shall fall within the limits given in Table – 10.2 with respect to type and quantity of bitumen and appropriate thickness.
Table – 10.1: Physical Requirements for Coarse Aggregates
Property Test Reference: Specification
Cleanliness (Dust) Grain Size Analysis IS:2386 - Part-1 Max 5% passing 0.075mm sieve
Particle Shape Flakiness and Elongation Index IS:2386 - Part-1 30% max.
Strength 1. Los Angeles Abrasion Value
2. Aggregate Impact Value IS:2386 Part-4
IS:2386 Part-4 Max 30%
Max 24%
Polishing Polished Stone Value BS:812 Part-114 Min 55
Durability Soundness:
1. Sodium Sulphate
2. Magnesium Sulphate
IS 2386 Part-5
IS 2386 Part-5
12% max.
18% max
Water Absorption Water absorption IS 2386 Part-3 2% max
Stripping Coating and Stripping of Bitumen Aggregate Mixer IS 6241 Minimum retained Coating 95 %
Water Sensitivity Retained Tensile Strength AASHTO T283 Min 80%
Table – 10.2: Combined Aggregate Gradation for Dense Bituminous Concrete
Grading 1 2
Nominal Aggregate Size 19 mm 13 mm
Layer Thickness 50-65 mm 30-45 mm
IS Sieve (MM) Cumulative % by weight of total aggregate passing
45
37.5
26.5 100
19 79-100 100
13.2 59-79 79-100
9.5 52-72 70-88
4.75 35-55 53-71
2.36 28-44 42-58
1.18 20-34 34-48
0.6 15-27 26-38
0.3 10-20 18-28
0.15 5-13 12-20
0.075 2-8 4-10
Bitumen Content % by mass of total Mix 5.0 – 6.0 5.0 – 7.0
Bitumen Grade (pen) 65 65
10.4 DESIGN MIX
Requirement of Mix: Apart from conformity with grading and quality requirements of individual ingredients, the mix shall meet the requirement of Marshall stability, Marshall flow (mm), Percent air voids, Minimum voids in mixed aggregates, Percent voids in mineral aggregates filled by bitumen, Binder percent by weight of total mix given in the following Table – 10.3:
Table – 10.3: Bituminous Concrete Mix Requirements
1 Marshall Stability (ASTM Designation-D-1559) on Marshall Specimens Compacted by 75 Compaction blows on each end. 9.0 KN
2 Marshal flow 2 – 4
3 Percent air voids 3 - 6
4 Percent minimum voids in mineral aggregate 12 - 15
5 Percent voids in minerals aggregates filled with bitumen 65 – 75
6 Loss of stability on immersion in water at 60° C (ASTM D 1075) Min. 75% retained strength
7 Binders content percent by mass of total mix Not less than 5.0%
Binder Content: The binder content shall be optimized to achieve the requirements of the mix set out in above Table - 10.3
Job Mix Formula: The following details of Job Mix Formula shall be submitted:
• Source and location of all materials
• Proportions of all materials expressed as follows where each is applicable:
(a) Binder type, and percentage by weight of total mix;
(b) Course aggregate/fine aggregate/Mineral filler as percentage by weight of total aggregate including mineral filler
• A single definite percentage passing each sieve for the mixed aggregate
• The individual grading of the individual aggregate fractions, and the portion of each in the combined grading
• The test results of Marshall Stability
• Test results of physical characteristics of aggregates to be used
• Mixing temperature and compacting temperatures.
Plant Trials - Permissible Variation from Job Mix Formula: After finalizing the job mix formula, plant trials shall be carried out to establish that the plant can be produced uniform mix conforming to the approved job mix formula. The permissible variations of the individual percentages of the various ingredients in the actual mix form the job mix formula to be used shall be within the limits as specified in the following Table – 10.4. These variations are intended to apply to individual specimens taken for quality control tests in accordance with Section 900 of MoSRTH Specifications.
Table – 10.4: Permissible Variations from the Job Mix Formula
Sl. No Description of Ingredients Permissible variation in %
1 Aggregate passing 19 mm sieve and larger + 7
2 Aggregate passing 13.2 mm , 9.5 mm + 6
3 Aggregate passing 4.75 mm + 5
4 Aggregate passing 2.36 mm, 1.18 mm, 0.6 mm + 4
5 Aggregate passing 0.3 mm, 0.15 mm + 3
6 Aggregate passing 0.075 mm + 1.5
7 Binder content + 0.3
8 Mixing temperature + 10° C
Laying Trials: After the plant trials have successfully completed, the laying trials shall then be carried out on a suitable area which may/may not be part of the works to demonstrate that the proposed mix can successfully be laid and compacted in accordance with project specifications. During these trials, the plant and laying/compaction equipment shall be established to produce satisfactory results.
The density of the finished paving layer shall be determined by taking cores after 24 hours of laying. The construction of permanent works shall be taken up after successful site trial satisfying the job mix formula and Project Specifications.
10.5 CONSTRUCTION METHODOLOGY:
The following sequence of activities shall be carried out for the construction of Bituminous Concrete:
a Bituminous Concrete mix shall then be prepared in a Batch Type Hot Mix Plant. The temperature of binder at the time of mixing shall be in the range of 150° C – 165° C and that of the aggregate shall be in the range of 150° C – 170° C. It shall be ensured that the difference in temperature between the binder and aggregate at no time exceeds 14° C. Mixing shall be thoroughly done to ensure that a homogenous mixture is obtained in which all particles of the aggregates are coated uniformly and the discharge temperature of mix shall be between 140° C to 165° C. The mixture shall be transported from the mixing plant to the point of use in suitable tipper vehicles. The vehicles employed for transport shall be clean and be covered in transit. A thin coating of diesel or lubricating oil may be applied to the interior of the vehicle to prevent sticking and to facilitate discharge of the material.
b The surface on which the BC mix is to be laid shall be cleaned of all loose and extraneous matter by means of mechanical broom or air compressor and tack coat shall be applied.
c The work of lying shall not be taken up during rainy or foggy weather or when the base course is damp or wet, or during dust storm or when the atmospheric temperature in shade is less than 10° C.
d The mix transported from the hot mix plant to the site shall be spread by means of self–propelled sensor paver with suitable screeds capable of spreading, tamping and finishing the mix to specified grade, lines and cross-section. The temperature of mix at the time of lying shall be in the range of 125° C - 160° C. Mixes with a temperature less than 125° C shall not be put into the paver spreader. Before the lane is compacted, the material along the unsupported edges should be butted and slightly elevated with tamping tool. This sets up the edges and permits the full weight of roller to bear on the extreme edge of mat.
e Longitudinal joints and edges shall be constructed true to delineating line parallel to the centre line of road. Longitudinal and Transverse joints shall be offset at least 250mm from those in lower course. All transverse joints shall be cut vertically to the full thickness of previously laid mix with asphalt cutter and surface painted with hot bitumen before placing fresh material. Cold longitudinal joints shall be properly heated with joint heater to attain temperature of 80° C before laying the adjacent material.
f After spreading the mix by paver, it shall be thoroughly compacted by rolling with a set of roller moving at speed not more than 5 km./hr. The initial or breakdown rolling shall be done with 80 – 100 KN static weight smooth wheeled roller. The intermediate rolling shall be done with a pneumatic roller of 150-250 KN weight having a type pressure of at least 0.7 MPa. The finishing rolling shall be done with 60 – 80KN weight smooth wheeled tandem roller. All the compaction operations, i.e. breakdown rolling and intermediate rolling can be accomplished by using vibratory tandem roller of 80 – 100KN static weight.
g The wheels of roller shall be kept moist to prevent the mix from adhering to them. Rolling shall be done longitudinally. The roller shall first compact material adjacent to joints and then work from lower to the upper side of the layer, overlapping on successive passes by at least one-third of the width of the rear roll or, in the case of PTR, at least the normal width of 300 mm. In portions with super-elevated and uni-directional camber, after the edge has been rolled, the roller shall progress from the lower to the upper edge.
h Rolling shall be continuous till the density achieved is at least 98% of the laboratory Marshall Specimen. Rolling operations shall be completed in all respects before the temperature of the mix falls below 90° C.
i In areas with restricted space where sensor paver can not be used, the material shall be spread, raked and leveled with suitable hand tools and compacted.
j Density of compacted layer shall be checked by core cutting method at the rate of one test for density per 250sq.m.area for the confirmation of achieved density is at least 98% of that of Laboratory Marshall Specimen.
k The surface finish of the completed construction shall conform to the requirements of Section 902 of MoSRTH Specifications.
l The newly laid surface shall not be open to traffic for at least 24 hrs after laying and completion of compaction.
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