Evaluation of Methods to Assess the Strength of Soil Cement Base

Abstract

Soil cement is a mixture of soil, portland cement, and water that, once compacted and cured, forms a strong and durable pavement base. Construction practices and variance among core strength data have led to questions concerning proper quality control practices and strength testing protocol regarding soil cement. A major concern in this area is strength assessment of the fully cured soil-cement roadbed. This concern has led to the following questions: Is it plausible to use field-molded specimens to evaluate the strength of soil-cement base? Is it plausible to use the dynamic cone penetrometer to evaluate the in-place strength of soil-cement base? In order to answer these questions, a field testing program was developed to evaluate the suitability of using the dynamic cone penetrometer based on ASTM D 6951, molded cylinder method based on ASTM D 1632, and the plastic mold method (Sullivan et al. 2014). The results from this research are aimed at providing guidance to ALDOT when specifying strength assessment parameters of soil-cement base. Based on the results from this research, the plastic mold method should be used for qualification of the soil-cement mixture along with field inspection testing. If the plastic mold compressive strength is less than or greater than the ALDOT specification on strength of soil cement base, the dynamic cone penetrometer should be used to determine the in-place strength of soil-cement base.