Strength benefit of sawdust/wood ash amendment in cement stabilization of an expansive soil

The investigation evaluated the strength benefits obtained by amending cement stabilization of an expansive soil by using saw dust ash (SDA), a waste generated in wood milling industries due to burning. The experimental program involved the preparation of cylindrical specimens of size 38 mm x 76mm for evaluating the unconfined compression strength (UCS) of the cement stabilized and amended samples cured for varying periods of 2 hours, 7, 14 and 28 days. Two cement contents of 2% and 6% by weight of soil were adopted to stabilize the soil. The SDA amended cement stabilized samples adopted SDA contents of 5%, 10% and 20% by weight of soil. Strength gain trends for the amended samples were also fitted based on the results of the UCS tests. In order to analyse benefits in pavement design and thickness reduction, the UCS values were used to predict the CBR value of the specimens based on which the reduction in pavement thickness was calculated for different traffic densities. The investigation revealed that 5% SDA amendment of cement stabilization can result in up to 26% increase in early strength and 20% increase in delayed strength. Based on the predicted CBR values, pavement thickness can be reduced up to 8.3%

Pozzolanic benefit of fly ash and steel slag blends in the development of uniaxial compressive strength of lime stabilized soil

This investigation involved the examination of pozzolanic benefits that resulted from the amendment of lime stabilization of a soil by using a combination of two industrial wastes viz. Fly ash (FA) and Steel Slag (SS). Two lime contents (6% and 8%), which represented the control specimens, were selected for stabilizing the soil, one above the Initial Consumption of Lime (ICL) and the other above the Optimum Lime Content (OLC), respectively. The lime to total solid waste ratio was maintained as 1:1, and the FA/SS ratio varied within the total solid waste content adopted for amending lime stabilization. The unconfined compressive strength (UCS) of the stabilized samples were determined by casting UCS specimens of 38 x 76 mm and cured for 2 hours, 7, 14 and 28 days. After curing, the specimens were strained until failure, to study the pozzolanic benefits of adding FA-SS. The results revealed that the addition of FA and SS improved the pozzolanic strength, ranging from 3.5% to 15%. The optimal dosage of FA and SS also varied with the lime content adopted. For the 6% lime content, a FA/SS ratio of 1:1 was found to be optimal, whereas for the 8% lime content, a FA/SS ratio of 3:1 was found to develop the maximum strength. The amendment of lime stabilization with FA/SS clearly brought about the difference in lime stabilization stages, unseen when only lime was adopted as stabilizer