The relatively high presence of silica found in the rocks in the quarries of the State plays a pivotal role in the damage of asphalt roads and severe pavement distress immediately after a heavy spell of rain in Kerala, says a joint study conducted by Kerala Highway Research Institute (KHRI), and department of Geology, University of Kerala, Thiruvananthapuram.
The research team headed by Sreejith G.H., Deputy Director, KHRI, and Anilkumar Y., Assistant Professor, University of Kerala, found that the silica content (SiO2) in rocks sourced from the quarries in the State—collected mainly from Thiruvananthapuram, Kollam, and Pathanamthitta districts—vary from 52.46% to 73.09%, posing a serious challenge to the engineering properties of the bituminous mixes used for road construction. Acidic rocks having an excess content of silica have a tendency to detach from bitumen in the presence of water.
The SiO2 content, found based on X-ray Fluorescence (XRF) analysis of 15 aggregate samples sourced from southern Kerala, varied from 52.46% to 73.09%. Out of the 15 samples, nine samples were highly acidic (i.e. SiO2 Content > 63%) and six were intermediately acidic in nature (i.e SiO2 ranged between 52% and 63%), says the study.
