After a test conducted by the Brihanmumbai Municipal Corporation (BMC) in August which revealed that 25 per cent of the cold mix used to repair potholes is substandard, the civic body has decided to go ahead with the same technology. The BMC introduced cold mix technology in 2012 to replace the conventional hot mix used for repairing potholes inspite of fierce opposition from corporators.
It contended that the hot mix for filling potholes washes away in the rain and hence is ineffective. “The cold mix is a tried and tested technology and better mix to fill up the potholes ahead of the rains. We have decided to continue with the use of cold mix. Though, we will also consider the corporators’s recommendations,” said chief engineer R A Pawar of the roads department.
While cold mix and hot mix have similar ingredients, hot mix is heated at a high temperature. The cold mix asphalt concrete uses asphalt and aggregate of bitumen, similar to hot mix which uses the same combination but at very high temperatures. The cold mix solutions settle down much quicker than the hot mixtures.
Following growing complaints of potholes in 2013, the civic administration, was forced to conduct a sample audit in which more than 15 per cent of 25 cold mix specimens collected from various potholes across the city, failed the quality-test. As part of the audit, a marshall stability test, which checks the samples’ bitumen content, load-bearing capacity at various temperatures, and mixture density, was conducted.
Based on the test results, the BMC penalised four contractors for malpractice and misappropriation of funds. The civic official added that they have already finalised contractors from the bids received for the Rs 28 crores tenders for pothole repairs this monsoon season. However, the bids received are 50 percent higher than the estimated base price fixed by the BMC.
The civic body, this year, has also introduced a series of additional qulaity parameters such as assessing the viscocity of the material contractors use. These chemicals are also used to toughen the material used in pothole-filling. The corporation will also make use of the three jetpatcher machines procured for quicker repair works of the roads. “We will employ our three jetpatcher machines, one each for the island city, eastern suburbs and western suburbs,” Pawar added.