Determination of Optimum Cement Content for Silty Sand Soil Stabilization as the Base Course

Abstract

The aggregate base course is important in the flexible pavement structure, requiring quality materials. In areas where quality material is difficult to find, local soil stabilization using cement is needed to obtain material to replace the aggregate base course. This study aimed to determine the optimum cement content in stabilizing sand-silty soil that meets the requirements specified in the General Specification of Highways 2018 for Road and Bridge Works and to find the effect of pH-soaking water. The research was conducted in the laboratory by testing the Unconfined Compressive Strength of soil cement using variations in cement content of 3%, 5%, 8%, and 10% of the dry weight of soil, soaking time of 3, 7, 14, and 28 days; and pH of soaking water (tap water with a pH value of 8, water with pH value of 4 (containing H2SO4), water with pH value of 9 (containing NaOH)). Cement content of 8% and 10% meets the minimum UCS value according to road specifications. The optimum cement content (which produces the UCS target specification value of 2353.60 kPa) is 9% on the seventh day. Soaking water with pH 4 and 9 decreased the UCS of soaking water with a pH value of 8. A soil cement base course can substitute an aggregate base course in areas with inadequate aggregate material with an 80% CBR value.