Influence of Changing Curing Temperature on the Strength of Cement-Treated Soil

The wet method of deep mixing involves mixing a binder-water slurry with soft in situ soil to increase the strength of the soil. Curing temperature is one of the most important factors that affect the strength of cement-treated soil. However, the ground temperature is not always consistent; it depends on the weather, season, region, and other environmental conditions. Additionally, the temperatures of cement-treated soil columns and adjacent in situ soil increase due to the heat generated from the cement hydration reaction in the elements and then decrease as the heat dissipates. This paper presents unconfined compressive strength (UCS) test results of cement-treated soil samples that the curing temperature was increased or decreased during the curing process. A fabricated lean clay (CL) was blended with a cement-water slurry. The prepared samples were cured in temperature-controlled water baths at 25°C and 45°C for up to 28 days. The portions of time at 25°C and 45°C and the order of curing at 25°C and 45°C varied. After the curing, UCS tests were performed to measure the strength of the samples. The test results show that a sample cured for a longer time at a higher temperature has a high UCS regardless of the order of curing temperatures. However, the effect of high curing temperature on the strength is more significant at a later curing time. In other words, with the same portions of curing time at 25°C and 45°C for two samples, a sample initially cured at the low temperature and then cured at the high temperature is stronger than the sample cured at the high temperature first. A strength development plot in the relationship between curing time and UCS has two logarithmic curves before and after the temperature change with different shapes.