Effect of Curing Stresses on the Mechanical Properties of Soil-Cement Mixed Materials-PPT Presentation

PPT Presentation

Pdf Summary

The DFI Technical Committee study investigated whether quality-control samples of deep soil-mixed (DSM) materials represent their in-situ strength, and how curing under confinement affects mechanical properties.<br /><br />Researchers developed a field consolidometer to apply confining stress to wet grab samples. Phase one included laboratory testing of cement-treated, well-graded fine-to-medium sand and data collection from four active DSM sites across North America. The laboratory mix was cured for 40 days under different stresses. Researchers also compared field results with core samples from four additional sites and findings from published studies.<br /><br />Across the laboratory and field datasets, unconfined compressive strength increased with curing stress. The size of the increase varied with soil type: fine-grained soils generally showed a larger relative strength gain than predominantly granular soils.<br /><br />The results suggest that testing wet grab samples cured without confinement can substantially underestimate the strength of soil-mixed material in the ground. This may affect project costs, schedules, and the effort required to meet specified strength targets. The findings are preliminary and indicate that curing conditions and soil type should be considered when interpreting quality-control test results.

Keywords

deep soil mixing

DSM materials

quality control

in-situ strength

confining stress

curing conditions

unconfined compressive strength

soil type

wet grab samples

field consolidometer