Evaluation of low strain shear moduli of stabilized sulfate-bearing soils using bender elements

Sulfate bearing soils are treated chemically with cement, lime or combination of both to enhance dynamic moduli, strength parameters and reduce swelling/shrinkage potentials. However, these treated soils heave due to the formation of highly expansive crystalline mineral, ettringite, which expands considerably when hydrated. Formation of ettringite results in sulfate induced heave and this process continues during the hardening of the stabilized soils. The present research is carried out to study variations of low strain shear moduli of chemically treated sulfate rich soils using bender elements and address the effects of sulfate induced heave problems in treated soils.; Bender elements, a fairly new, non-destructive shear wave propagation technique was successfully applied to assess low strain shear moduli of chemically treated sulfate rich soils. Hydrated ettringite, which was formed in chemically treated sulfate rich clays when cured under water, affected stiffness properties of treated clays. Percent increases in stiffness properties of lime treated clays were lower than those of cement treated clays. Treated soil samples at 10,000 ppm sulfate level showed considerable swelling while no major detrimental results were observed at 1000 ppm sulfate level. The low strain shear moduli values can be indirectly used to identify sulfate induced heave problems in treated clays.