Soil Property Criteria for Rammed Earth Stabilization

This study relates value ranges of natural soil properties (plasticity, texture, and shrinkage) to the degree of predisposition of soils to stabilization for rammed earth wall construction. A total of 219 strength determinations were made on 104 soils compacted and stabilized with cement and/or lime and/or asphalt. Using a $2\mathrm{MPa}$ compressive strength criterion as the measure of stabilization success, soil property value ranges were related to the proportion of samples exceeding the criterion. Linear shrinkage (LS) and plasticity index (PI) are found to be the best discriminators of soil predisposition, with textural variables being useful secondary discriminators. “Favorable” soils, with stabilization success rates of $\ge 80\%$ , include those with: (1) $\mathrm{LS}<6.0\%$ and $\mathrm{PI}<15\%$ ; and (2) LS 6.0–11.0%, PI 15–30%, and sand content $<64\%$ . These soils were stabilized with treatments averaging 4.2% cement and 1.8% lime, with individual treatments ranging from 4–8% total cement and/or lime. “Unfavorable” soils, with stabilization success rates of $<60\%$ , include those with LS 6.0–11.0, PI 15–30, and sand content $\ge 64\%$ , or with $\mathrm{LS}>11.0$ , $\mathrm{PI}>30$ . These findings should assist rammed earth engineers to more easily select a suitable soil and to minimize resources spent on preconstruction stabilization trials.