Geotechnical and environmental evaluation of lime-cement stabilized soil-mine tailing mixtures for highway construction

Lime-cement was used as a stabilizing binder in a ratio of 1:2 to treat Lateritic Soil-Mine Tailings (LMT) mixtures. Strength characteristics and environmental impact of the Lateritic Soil-Mine Tailings Binder Mix in highway construction was evaluated using a series of laboratory tests. Results of the geotechnical tests showed that the properties of the soil sample improved with the addition of mine tailings and binder. There was an increase in the maximum dry density with a decrease in the optimum moisture content. There was also an increase in the strength of the lateritic soil, this was evident from the California Bearing Ratio and the Unconfined Compressive Strength values. The environmental performance evaluation was determined by the leaching test, conducted on the LMT sample to determine the capability of the binder in retaining heavy metals. The results of the leaching test show that the binder was able to reduce the heavy metals in the leachate below the regulatory level, with the exception of barium and chromium. Mineralogical analysis done on the leached samples revealed that the binder was able to immobilise the mine tailing minerals that could adversely affect the environment in the soil matrix.