Strengthening Clayey Soils Using Aggregate Blending and Cement Stabilization

A key strategy employed by engineers to increase the longevity of roadways is specification of cement treatment, or stabilization, of the soil layer underlying the roadway to improve its strength and durability. Different soils require different amounts of cement to achieve the desired material properties. When a soil contains clay, an excessive amount of cement may be required to achieve the target strength. When a soil requires a high amount of cement, such as the soil studied in this research, alternative approaches are desirable because of the relatively high price of cement. One potential method of reducing the cement requirement involves the addition of crushed stone, or aggregate, to the soil. The objective of this research was to investigate the use of aggregate blending in conjunction with cement stabilization for improving the strength of a clayey soil. Samples of the clayey soil were mixed with varying amounts of cement and aggregate, compacted, cured for 7 days, and then subjected to compressive strength testing. The results indicate that an aggregate addition of 40% and a cement concentration of 5% by total dry weight of soil and aggregate can achieve a 7-day unconfined compressive strength of 3.45 MPa (500 psi), which is recommended for roadway base materials in cold regions.