2. Relevant Process/Specifications:
The Construction Manager/Project Engineer is responsible for the asphalt paving works.
The Civil Construction Contractor’s Safety Officer shall ensure that necessary work permits are availed before the work commences and that the work is carrying out in safe manner.
The responsibility of the survey activities lies with asphalt paving work subcontractor. The survey team of civil construction contractor shall verify the data frequently.
Inspection and testing activities shall be controlled by the QC Engineer of Civil Construction Contract or through the site laboratory of Company.
4. Plants and Equipment:
Bitumen spray tankers, asphalt paver, Tandem steel roller, hand rollers, asphalt batching plant, etc.
5. Execution Procedure:
Prior to Commencement:
Prime importance shall be given for personnel safety and protection of utility lines/services. It shall be ensured that the personnel involved are aware about the Company Safety regulation and confirm that the machineries are regularly maintained. Further to above, the following key points shall be considered important.
a. Copies of drivers/operator’s license vehicle’s registration and security passes to be submitted to Company safety department before commencing the work.
b. All moving vehicle/equipment shall have reverse horn.
c. Transporting of persons per vehicle is restricted to the number of seat belts available in the pickup.
d. Deep excavations shall be adequately shored, barricaded and warning signs & lights shall be posted.
e. Road safety signs/road diversion signs shall be installed wherever applicable for the safe movement of vehicles and equipment.
f. All major equipment shall be tested and certified by Third Party prior to mobilization to site.
Existing Services and Facilities:
a) Before commencement of the work, ascertain the nature and location of all existing above and underground services at site by visual survey and reviewing the service layout drawing (if available)
If any protection, re -routing, termination or removals of services are required for the smooth progressing of work, it shall be discussed and written approval shall be obtained from employer/ company as appropriate. For service protection, approved method of protection shall be adopted.
b) A warning tape shall be tied at a distance of 2 meters away from the services/as warning sign, to restrict the movement of the equipment.
a) Establish and protect sufficient number of stations to re-establish the stations if they are disturbed during work.
b) Post wooden stack for line and gradient of the road.
c) The existing sand tracks shall be blocked, re-routed and traffic diversion signs shall be posted prior to the commencement of the work.
The execution procedures shall be divided into following sections, which are:
a) Prime Coat.
b) Binder course.
c) Tack coat.
d) Wearing course.
a) Prime Coat:
Quality of Primer should be as per BS1707 or 1S:217, IS: 454 and IS: 8887.
Immediately before applying the prime coat (which shall be preliminarily approved), the full width of the surface shall be cleaned with compressed air.
i) The bituminous material for the prime coat shall be applied by means of bitumen spray tankers.
ii) This shall be applied in a single layer at the rate of 0.7 – 1.5 liters /sq.m and at a temperature not exceeding 70? C. This surface shall be cured for 24 hours.
iii) The over spread area shall be cured more than 24 hours/ until excess prime coat is evaporated.
b) Binder Course:
Quality of Binder should be as per AASHO-T182 or IS: 73, IS: 217,1S:454 and IS: 8887.
i) Immediately before paving the binder course material, the surface of the prime coat shall be cleaned with compressed air and shall be ensured that the surface is dry.
ii) The hot asphalt mix shall be brought from the mixing plant by 6 wheel trucks or trailers. Upon arrival at site, the asphalt mix shall be dumped into the asphalt paver.
iii) The asphalt paver shall lay the material to the required thickness and level.
iv) The mix shall be compacted as soon as possible after spreading the material. Tandem rollers shall follow the laying operation to carry out breakdown rolling up to temperature of 110- 120? C. Pneumatic tired rollers and tandem rollers shall follow the breakdown rolling and sufficient passes shall be made to achieve the required compaction.
Rolling shall start from the sides and proceed toward the center. Each trip of the roller shall overlap the pervious trip by at least 30 cm. Roller wheel shall be kept moistened. The roller shall be capable of reversing without backlash and shall be free from worn parts.
Heavy rollers shall be used to complete all rolling including elimination of waves caused by the lighter rollers. Full compaction shall be obtained before the asphalt temperature reaches 100° C. Compaction shall be in accordance with specification of relevant standard.
v) The construction joints shall be prepared by cutting the layer vertically down by means of asphalt saw cutting machine or with jack hammer. The joint shall be cleaned well by compressed air and tack coat material shall be applied on the vertical and horizontal surface for better bonding. Extremely good care shall be taken when asphalt is laid at construction joints.
vi) The areas inaccessible for heavy rollers shall be compacted with plate compactors or hand tampers. After reaching the base course top level, suitable fill material (dune sand) shall be dumped to the top level of base course on the sides of road shoulders. It shall be leveled, shaped (1:6 ratios) and compacted to 90% maximum dry density.
c) Tack Coat:
i) The material (which shall be primarily approved) shall be applied at the rate of 0.3 to 0.6 lit/ sq.m at the temperature not exceeding 54 °C above the binder and at where there is a joint with existing asphalt surface.
ii) The surface shall be cured for the period as per manufacturer’s recommendations until a tacky surface is visible.
d) Wearing Course:
i) The hot asphalt mix shall be spread over the cured surface of tack coat by automatic asphalt paver to the required profile and thickness.
ii) The mix shall be compacted as soon as possible after spreading the material. Tandem roller shall follow the laying operation to carry out breakdown rolling up to a temperature of 110- 120? C.
Self propelled rollers and Tandem rollers shall follow the breakdown rolling and sufficient passes shall be made to achieve the required compaction.
Rolling shall start from the sides and proceed toward the center. Each trip of the roller shall overlap the previous trip by at least 30 cm.
Roller wheels shall be kept moistened. The roller shall be capable of reversing without backlash and shall be free from worn parts. Heavy tandem roller (CC-41) shall be used to complete all rolling including elimination of waves caused by the lighter rollers Full compaction shall be obtained before the asphalt temperature reaches 80? C. Compaction shall be in accordance with specification of relevant standard.
iii) Traffic shall not be allowed on this layer until it is properly cooled, a minimum period of 12 hours shall be considered after the completion of the rolling.
iv) The test holes shall me made good with hot asphalt mix and compacted using Marshal Hammer.
Inspection and Testing:
Testing shall be conducted by Company’s third party site laboratory.
Relevant QC records shall be raised by Civil Construction Contractor’s QC Engineer. Also tests shall be carried out as per the Field Quality Control Plan of Asphalt Work.