Additives for Soil-Cement Stabilization

Soil-cement stabilization is commonly used in road construction applications when temperatures exceed 10°C. At lower temperatures, cementitious reactions proceed more slowly and strength development remains incomplete. As a component of a larger research effort, this paper reports on the use of sodium chloride (NaCl) and calcium chloride (CaCl₂) for enhancing strength gain at curing temperatures of 2°C and 10°C. The results are mixed depending on the soil, with both increased and decreased unconfined compressive (UC) strength at both temperatures for curing durations of 3 and 7 days. For example, one local soil (Johnston County, NC) mixed with 6% Portland cement and 1.5% sodium chloride (by volume in molding moisture content) resulted in an increase in UC strength from 1748 to 2303 kPa when cured at 10°C for 7 days. Another local soil (Buncombe County, NC) responded negatively to NaCl addition. Clay content and overall composition are postulated as controls on additive efficacy.