Effect of Fly Ash on Cement Admixture for a Low Plasticity Marine Soil

The deep cement mixing (DCM) method is one of the popular methods of groundimprovement techniques for enhancing the bearing capacity and reducing settlements of thick deposits of soft clay with high water content. High cement content, of the order of 10 % to 25 %, are often used in practice. To reduce the requirement of cement, an attempt is made in the present study to replace the cement partially with fly ash, as a fly ash-cement composite. Different percentages of Class F fly ash (10 %, 20 %, and 30 %) to Ennore marine clay with different proportions of cement (10 %, 15 %, and 20 %) were added and tested. The optimum clay water content at which maximum strength is achieved was determined for various mixes based on unconfined compressive strength tests. A detailed study showed that addition of 20 % Class F fly ash is effective in all combinations. The behavior of the composite under one-dimensional consolidation was also tested.