Stabilizing Potential of Cement and Fly Ash Mixture on Expansive Clay Soil

Soil treatment or stabilization is highly recognized by geologist and engineers as a very important process in improving the performance of weak or marginal soils and make them perform better as highway materials. This study was an investigation of the potential of stabilizing an expansive clay soil with the combination of cement and fly ash. The expansive clay soil samples were first subjected general classification tests where three classes of samples evolved; 12% cement optimal mix, 9% cement plus 3% fly ash optimal mix and the 0% (unstabilized) natural clay soil sample. The three different classes of samples were then subjected to engineering tests; Maximum Dry Densities (MDD), Optimum Moisture Contents (OMC), California Bearing Ratio (CBR), Unconfined Compression and the Undrained Triaxial test. The results showed that the soil sample stabilized with a mixture of 9% cement plus 3% fly ash is better with respect to MDD, OMC, Bearing Capacity and Shearing Resistance, when compared with sample stabilized with 12% cement plus 0% fly ash. This shows that the addition of a certain percentage of fly ash will improve the stabilizing potential of cement on an expansive clay soil.