Road construction materials
Murum for Road Construction Work :
It shall be granular and gritty. It shall be free from dust, all rubbish, and any organic materials as well as clods of black cotton soils. The material shall be got approved prior to its use in road construction.
The material shall be stacked on a level ground. If the item is only for supplying of murum, then it shall be measured in CuM. The rate shall include digging the murum, supplying at site, conveying with all lead and lift and stacking the same at site. The rate includes all tolls, duties, fees, royalties etc.
Sand for Road Construction Work:
The sand shall be from a river or nala or sea. It shall be clear, sound, properly graded; free from organic material, silt, clay etc. and it shall be well graded.
Metal for Road Construction Work:
The stone metal shall be hard, sound, durable, stone of close texture as is locally available and reasonably free from decay and weathering. It shall be angular or cubical. Round elongated or flaky metals shall be rejected. No round or oblong pebbles or angular chips shall be allowed. The size of the metal shall be 40mm to 63mm . All disintegrated stone shall be rejected. The metals shall be tested for Abrasion value, Aggregate Impact value and Flakiness Index in standard laboratories before the material is put to use and they shall conform to relevant IS codes. Metal shall be stacked at site on fairly level ground.
Rolling of Road in construction of bituminous road
A power/vibro roller shall, as a rule, be not less than 8-10 tonnes but if at any time still heavier rollers are required on the works. A hand roller should not be less than a ton. Rolling shall progress from edges to the centre of the road in strips parallel to the centre line of the road. Rolling shall be done by lapping uniformly each preceding rear wheel track by at least one half width of the track.
On super elevations, rolling shall be started at inner edge and shall progress towards outer edge. During and after rolling, the surface shall be checked for grade and camber, with camber plate. The roller shall be started, worked or stopped without jerks. Rolling shall normally be done for a minimum length of 100 M.
Construction of bituminous road-Process in Bituminous Road Construction
Surface dressing of road preparation of sub grade –
The high portion of ground shall be cut down and /or hollows and local depression shall be filled up to 300 mm to bring the sub grade to required level and camber. The gradient and camber/slope should be maintained as per requirement so as to give an even, neat and tidy look to the work.
The area requiring cutting more than 300 mm, quantity of cutting shall be paid separately under relevant items of earthwork for the quantity exceeding 300 mm depth of cutting. Similarly when quantity of filling exceeds the available quantity of earth for filling such filling shall be paid separately under relevant item of earth work. This includes road formation in embankment where filling and rolling is involved.
Preparation of Sub grade of Road-
The sub grade shall be levelled to the proper level and camber by filling depressions with excavated material and cutting of protuberances.
The sub grade shall be made to have as nearly as practicable, a uniform bearing layer and all hard spots therefore be properly excavated and refilled. All soft and spongy parts of the sub grade shall be excavated and refilled with approved materials of 15 cm layers for the same reason.
The cost of excavation in excess of 300 mm depth will be paid under the item for excavation. The sub-grade shall be watered as directed at least 12 hours before rolling the subgrade using 8-10 MT smooth wheeled road rollers to achieve desired compaction.
Proper accesses should be prepared for the roller to get to the sub-grade and all manholes frames and covers should be removed and replaced by plates of adequate strength free of cost whenever they interfere with the free rolling of the sub grade. Also all chamber to be filled with sand filled gunny bag to transfer, vibration and to safeguard the chamber
After rolling the camber, super elevation and longitudinal slope etc. of the sub grade shall conform in shape to those of the finished road surface.
This should be checked with the help of levelling instrument, level strings and camber board as requirement. When subgrade consists of black cotton soil , a thin layer of murum or coarse sand shall be provided below any base course, watered and rammed and rolled tightly. Supply and filling sand or murum shall be paid under relevant item.
Minimum value of CBR for subgrade soil should not be less than 10.
Measurement of Preparation of Sub grade of Road:
Measurement of Preparation of Sub grade of Road is in SqM.
Laying Base course For Water Bound macadam –
65 mm nominal size or as specified, metal shall be spread over the prepared base to a thickness of 130 mm for consolidated one or two layers as specified, the metal layer dry and wet shall then be rolled and consolidated by a 8-10 tonne power roller to achieve consolidated thickness of 100 mm.
After the dry rolling is completed, smaller size stones, grit, dust, sand etc. shall be spread The thickness of the consolidated layer after completing all the operations described below shall be less than 100mm then blinding material like murum or red bajri shall be laid and watered and rolled. Rolling shall start from edge of road and proceed towards the crown in longitudinal strips overlapping on successive strips by at least one half the width of the rear wheel of the roller.
The operation shall continue till no visible settlement of the metal or movement under the roller is observed. The gradient and camber shall be checked from time to time by means of level, stacks, strings camber board etc. Any depression or hump shall be corrected by removing completely the metal layer there at the spot and rolling the same satisfactorily.
Moderate sprinkling of water and rolling shall be continued and stone dust shall again be spread if required till all the voids are completely filled and the movement of metal under the wheel ceases. If there is excess powder the same shall be removed lightly by brooms.
The surface shall be checked for camber etc. the unevenness or undulations shall be rectified as required. The whole surface shall be then watered, extra powder added if required, brushed and rolled to obtain a mosaic surface. This type of surfaces shall be maintained till upper layer is laid
Strength of the base course Water Bound macadam :
It shall be ensured prior to actual execution that material to be used in the sub- base satisfy the requirements of CBR and other physical requirements when compacted and finished. This shall verified by performing CBR tests in the laboratory as required on specimens re-moulded at field dry density and moisture content and any other tests for the “quality” of materials , as may be necessary.
Measurement of Laying Base course For Water Bound macadam
Measurement of Laying Base course For Water Bound macadam in SqM for the consolidated thickness laid.
Laying wearing course in construction of bituminous road-
50 mm metal shall be spread, in one or two layers as specified, over the prepared base to a thickness of 75 mm consolidated each and the rate of spreading grit shall not be less than 10 to 15 cft/100 sq.ft. The other operations such as rolling watering.
Strength of the wearing course in construction of bituminous road-
It shall be ensured prior to actual execution that material to be used in the sub- base satisfy the requirements of CBR and other physical requirements when compacted and finished. This shall verified by performing CBR tests in the laboratory as required on specimens re-moulded at field dry density and moisture content and any other tests for the “quality” of materials , as may be necessary
Minimum value of CBR for Granular subgrade as per morth
Measurement of the wearing course in construction of bituminous road :
Measurement of the wearing course in construction of bituminous road be measured in SqM for the consolidated thickness laid.
Premix carpet in road construction-
laying 20mm thick layer of hot asphalt & aggregate pre-mix carpet over the wearing course
Laying and compacting carpet of 20mm thickness in single course composed of suitable small sized aggregates premixed with bituminous binder on prepared base. The surface shall be brushed free of any loose blinding material out of the voids into which it has set. The surface then shall be tested for depression, which shall be made up by re-metalling and blinding with aggregate of a size equivalent to the depth of the depression.
A. tack coat in road construction-
Bitumen 80/100 of approved brand, heated to a temperature of 350 Deg. F. shall then be applied evenly to the cleaned WBM surface by means of a pressure distributor at the rate of 4.0 kg per 10 SqM.
B. Proportioning of materials-
0.18 CuM of stone aggregates of 13.2 mm; passing 22.4 mm sieve and retained on 11.2 mm sieve and 0.09 CuM stone aggregates of 11.2 mm size passing 13.2 mm sieve and retained on 5.6 mm sieve i.e. total 0.27 CuM per 10 SqM shall be premixed with 9.5 kg of bitumen for 13.2 mm and 5.1 Kg for 11.2 mm aggregates. The stone aggregate shall be hot & dry and contain not more than 2% moisture before use. It shall be first screened of dust, measured and heated. Bitumen of approved make and grade shall be used.
c. Preparation of Premix carpet in road construction-
Hot mix plant of appropriate capacity and type shall be used for preparation of mix material. The hot mix plant shall have separate dryer arrangement for heating aggregates and pug mill for mixing aggregates and binder. The temperature of the bitumen binder at the time of mixing shall be in the range of 150 to 163 Degree C and that of aggregates 155 to 163 Degree C so as to discharge the mix at 130 to 60 Degree.
While the bitumen 80/100 is still hot the surface shall be laid evenly with premix by suitable means and rolled with smooth wheeled 10 T rollers in required line level and camber. Rolling shall begin at edge and progress towards centre longitudinally, except on the super elevation and unidirectional cambered portion, it shall progress from the lower to upper edge parallel to the centre of the pavement. Any soft spot or depressions detected at a later date shall be made up.
Measurement of Premix carpet in road construction-
Measurement of Premix carpet in road construction in Sqm.
Seal coat with hot bitumen in construction of bituminous road-
Laying premix seal coat comprising of a thin application of fine aggregates premixed with bitumen binder is applied to water proof road, to seal the surface, to prevent oxidation due to air circulation to strengthen bitumen surface or to improve texture, reduce porosity and tendency to disintegration.
Seal coat with hot bitumen- Treatment consist of laying premixed stone chippings 0.09 CuM (aggregates) of 6.7 mm size defined as 100 % passing from 11.2 mm sieve and retained on 2.36 mm sieve mixed with 9.8 Kg bitumen of approved make and grade per 10 SqM.
The binder shall be heated in boilers of suitable design to the temperature appreciate to grade of bitumen , and the seal coat applied through suitable means and rolled by smooth wheeled roller Tandom Roller- vibratory of 10 T including spreading required quantity of dry sand/ aggregate dust and removing the excess sand / dust after 2-3 days after opening the road for traffic.
Important Note for construction of bituminous road-
All specification for road work for Clearing and Grubing , Earth work, Subgrade, Granular Gsb, WMM and Asphalt work, Dry lean cement concrerte & PQC would be as per specifications of MORTH.
Measurement of Seal coat with hot bitumen in construction of bituminous road-
Measurement of Seal coat with hot bitumen in construction of bituminous road is in Square Meter.
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