Experimental Investigation of the Effects of Cement Treatments on the Swelling Potential of Clayey Soils-Paper

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The study examined whether cement can economically reduce the swelling potential of expansive clay soils. Researchers tested three Southern California soils—Inglewood, Laguna Niguel, and Long Beach—using standard laboratory procedures, including the ASTM Expansion Index test. Cement was added at varying percentages by dry soil mass, and the samples’ expansion indices (EI) were measured.<br /><br />All three untreated soils had high expansion indices: 120 for Inglewood, 140 for Laguna Niguel, and 116 for Long Beach. Cement reduced expansion in every soil, but effectiveness differed substantially. At 5% cement, EI fell to 17 for Inglewood and 24 for Long Beach; Laguna Niguel required about 8% cement to reach an EI of 10. All three soils reached an EI of zero at 10% cement. The results indicate that each soil has a distinct cement content at which swelling drops markedly, and that soil composition—including mineralogy—affects treatment response.<br /><br />The study also examined relationships between soil properties and expansion. Plastic limit did not appear to be a reliable predictor, while plasticity and clay activity were considered relevant; however, the limited number of samples restricts broader conclusions. The authors developed a two-variable equation using plasticity index and cement content to estimate EI for soils with characteristics similar to those tested, particularly in Southern California.<br /><br />The findings suggest cement treatment may offer an alternative to costly excavation and replacement of expansive subgrades. However, the proposed equation is based on only three soils and should be applied cautiously to dissimilar materials. Further testing, especially to account for mineralogy and variability in soil response, is needed before generalizing the results.

Keywords

expansive clay

cement stabilization

swelling potential

expansion index

ASTM test

soil treatment

plasticity index

soil mineralogy

Southern California soils

subgrade improvement