Effect of Magnesium Sulfate on the Unconfined Compressive Strength of Cement-Treated Soils

Abstract

Cement-treated soil is widely used as highway base, subbase, and roadbed material because there is a widespread source, and it has low cost and high compression strength. However, there are cases where an area using the cement-treated soil may be affected by corrosive ions, such as sulfate ion (SO42−), chloride ion (Cl−), magnesium ion (Mg2+), etc., because of industrial-activity-induced ground contamination, as well as seawater intrusion. In this paper, the effect of magnesium sulfate (MgSO4) on the unconfined compression strength (qu) of cement-treated soil has been investigated experimentally under two conditions: (a) the sample is steeped in MgSO4 solution, and (b) MgSO4 is added into the sample. The main control parameters in this research include cement content (10 %, 15 %, 20 %, and 25 %), concentration of MgSO4 (0.01 mol/l, 0.05 mol/l, and 0.1 mol/l) and curing time (7 days, 14 days, and 28 days). The test results show that the effect of MgSO4 on the qu value is greater when the sample was steeped in MgSO4 solution than by adding MgSO4 into the sample. When the sample was steeped into MgSO4 solution with a concentration of 0.05 mol/l, the qu value was increased, and further increased the concentration-reduced qu value. Also, the test results indicate that qu increased with the increase of cement content. The variation tendencies of the qu value with curing time are different for two different testing conditions.