Road Construction

Road Construction

Road construction is not just building a road. It is the preparation of a complete environment for building and living, above as well as underground. Without a proper foundation you cannot build a solid road. The type of foundation depends on the soil type. That is why CDS has geotechnical experts. In our laboratory we can examine the soil type and together with our technical and quality department we will propose a type of foundation suitable for the project.

A good way to restructure our large road network and giving it a strong foundation again, is by applying bit foam using a special method. The road is milled using a special technique. The existing road construction is milled into small pieces and at the same time the bit foam technique is applied by adding water, bitumen, and cement. This creates a new fortified foundation on top of which a new layer of asphalt will be laid. This method creates a road that will last for many years, and reduces costs and labor by at least 20% while having a lesser impact on the environment. A green way to re-use the existing road.

The asphalt truly tops things off. Our Team will bring the finishing touch to the road. Our years of experience will guarantee you a job according to your wishes.

Steps of Road Construction
Road construction consists of various steps such as preparation of base course, application of bituminous coat, placement of bituminous mix, rolling and check for quality etc. which are discussed.

1. Preparation of the existing base course layer

The existing surface is prepared by removing the pot holes or rust if any. The irregularities are filled in with premix chippings at least a week before laying surface course. If the existing pavement is extremely way, a bituminous leveling course of adequate thickness is provided to lay a bituminous concrete surface course on a binder course instead of directly laying it on a WBM.

2. Application of Tuck Coat

It is desirable to lay AC layer over a bituminous base or binder course. A tack coat of bitumen is applied at 6.0 to 7.5 kg per 10 sq.m area, this quantity may be increased to 7.5 to 10 kg for non-bituminous base.

3. Preparation and placing of Premix

The premix is prepared in a hot mix plant of a required capacity with the desired quality control. The bitumen may be heated up to 150 – 177 deg C and the aggregate temperature should not differ by over 14 deg C from the binder temperature.
The hot mixed material is collected from the mixture by the transporters, carried to the location is spread by a mechanical paver at a temperature of 121 to 163 deg C. the camber and the thickness of the layer are accurately verified. The control of the temperatures during the mixing and the compaction are of great significance in the strength of the resulting pavement structure.

4. Rolling

A mix after it is placed on the base course is thoroughly compacted by rolling at a speed not more than 5km per hour.
The initial or break down rolling is done by 8 to 12 tonnes roller and the intermediate rolling is done with a fixed wheel pneumatic roller of 15 to 30 tonnes having a tyre pressure of 7kg per the wheels of the roller are kept damp with water.
The number of passes required depends on the thickness of the layer. In warm weather rolling on the next day, helps to increase the density if the initial rolling was not adequate. The final rolling or finishing is done by 8 to 10 tonne tandem roller.

5. Quality control of bituminous concrete construction

The routine checks are carried out at site to ensure the quality of the resulting pavement mixture and the pavement surface.
Periodical checks are made for
a) Aggregate grading
b) Grade of bitumen
c) Temperature of aggregate
d) Temperature of paving mix during mixing and compaction.
At least one sample for every 100 tonnes of the mix discharged by the hot mix plant is collected and tested for above requirements. Marshall tests are also conducted.
For every 100 sq.m of the compacted surface, one test of the field density is conducted to check whether it is at least 95% of the density obtained in the laboratory. The variation in the thickness allowed is 6mm per 4.5m length of construction.

6. Finished surface

The AC surface should be checked by a 3.0 m straight edge. The longitudinal undulations should not exceed 8.0 mm and the number of undulations higher than 6.0 mm should not exceed 10 in a length of 300 m. The cross-traffic profile should not have undulations exceeding 4.0mm.

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