n a move to adopt green technology, the Local Self-Government Department (LSGD) has started using emulsion-based cold mix instead of hot bitumen mixes for laying roads in the State.
Cold mixes are prepared by mixing aggregates with bitumen emulsion at ambient temperature compared to the hot mix prepared at a temperature of 155 degrees C that leads to emission of hydrocarbon and suspended particulate matters.
The Vengodu-Cheroor road, near Pothencode, in the capital district under the LSGD Sub-Division, Pothencode, has become the first stretch to get the bitumen emulsion-based cold mix. “The 3-metre road shows good finishing. It feels harder than the conventional mix. We have been constantly monitoring it since March 17,” an engineer associated with the project told The Hindu .
The trial was carried out on the 100-metre damaged bituminous surface, over which the premix chipping carpet with seal coat was laid using bitumen emulsion. The cold mix was prepared in a concrete mixer with 13.2 mm and 11.2 mm locally available aggregates in 2:1 ratio and premix MS emulsion.
The blended aggregates were charged in the mixer and one per cent water was added to damp the aggregates. A 6 per cent emulsion (MS) by weight of aggregates was added into the mixer. The laying of Pre Mix Carpet (PMC) was done manually by spreading cold mix on tack coated existing road. After 20 minutes, the tack coat emulsion changed to black from brown colour.
The compaction was done with 8-10 tonnes roller and the seal coat was carried out on PMC to fill the voids. The stretch was opened to traffic within an hour of completing the work.
The cost and energy saving, protection of environment, decrease in carbon footprint, use of damp aggregates are the advantages. Besides, round-the-clock work can be carried out as construction with cold mix is feasible in cold climate and even during the monsoon season with wet aggregates. The method can also be adopted in forest areas vulnerable to fire, he said.
The stretch was laid under chief engineer P.R. Sajikumar by a team led by executive engineer S. Anwar Hussain, assistant executive engineer Ganga R.S., assistant engineer Shiju Chandran R. and overseer Krishnakumar. The technical team of M/s Hindustan Colas (HINCOL) assisted them.
The department has plans to use the technology on more rural roads. The construction with cold mix is cheaper by 15 to 20 per cent.
The Vengodu-Cheroor road is the first stretch to get the bitumen emulsion-based
cold mix.
