Influences of Mixture Proportions and Test Conditions on the Strength and Stiffness of Wet-Mixed Soil and Cement-PDF

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The report investigates how laboratory procedures, test conditions, and mix proportions affect the strength, stiffness, and workability of wet-mixed cement-treated soil. Tests used a single manufactured lean clay and Type I/II Portland cement, with varying cement contents, slurry water-to-cement ratios, curing periods, temperatures, and confining pressures.<br /><br />End-face preparation had little overall effect on unconfined compressive strength (UCS) when performed carefully. Grinding and sawing with hand trimming gave the most consistent results; neoprene pads were not recommended because they could cause atypical splitting failures. Local displacement measurement devices had only small effects on UCS, but they measured stiffness more reliably than machine-based displacement readings, which were affected by equipment slack and compliance.<br /><br />UCS increased with curing time and generally decreased as the total water-to-cement ratio increased. A four-parameter prediction relationship that also accounts for mixture dry unit weight fit the results better than a model based only on curing time and water-to-cement ratio. Higher curing temperatures increased strength, although the temperature data were limited and showed scatter. Confining pressure had a particularly strong effect on post-peak strength: specimens in unconsolidated-undrained triaxial tests retained substantially more strength at large strains than unconfined specimens.<br /><br />The study also found that mixture consistency, measured as undrained shear strength with a miniature vane, varied with mixture water content and time after mixing. Combining consistency and UCS predictions can help identify mix designs that meet performance and workability targets while minimizing cement use.<br /><br />Because the research used only one soil and binder, the authors recommend further testing across soil types, binders, curing conditions, and measurement methods.

Keywords

wet-mixed cement-treated soil

unconfined compressive strength

laboratory procedures

mix proportions

curing time

water-to-cement ratio

confining pressure

stiffness measurement

workability

miniature vane test