Improvement of Soft Bangkok Clay by Cement Mixed with Corncob Ash and Limestone Powder

Abstract

This research aims to study quality improvement of soft Bangkok clay by mixing cement with industrial wastes, corncob ash and limestone powder using Unconfined Compression and X-Ray Diffraction (XRD) tests. The study showed that the optimum ratio of the compounds which from preliminary test, cement : corncob ash : limestone powder is 65:20:15. After mixing the binder with soft Bangkok clay through density controlled compaction at the ratio of 10%, 12%, and 14% by wet unit weight for quality improvement, it was found that the unconfined compressive strength of soil-cement mixed with corncob ash and limestone rises in accordance with the increasing amounts of cementitious materials and curing time. Also investigated was the strength development mechanism by means of XRD. The result revealed that Calcium Silicate Hydrate (CSH) increases while Dicalcium silicate (C2S) and Tricalcium Silicate (C3S) decrease. In conclusion, this study showed that the appropriate amount of the binder, the mixture of cement, corncob ash and limestone powder, has the potential to improve the strength quality of soft clay.