Effects of metakaolin and sodium silicate treatment on highwater content dredged clay for improved construction fill performance

Abstract

This study experimentally investigated the strength characteristics of metakaolin (MK) and sodium silicate (SS) treated dredged clay at high water content for use as construction fills. A series of laboratory tests including direct shear tests, unconfined compression tests, SEM and XRD tests were carried out to systematically evaluate the effects of water content, sodium silicate modulus, curing agent content, and curing time on the strength behavior of MK and SS treated dredged clay samples. The direct shear test results showed that the shear strength at a given vertical stress consistently increases with the increase of curing agent content and curing time while decreasing with the modulus of SS. Both cohesion and friction angle increase with increasing curing agent content and curing time, while reducing with the increasing modulus of SS. Unconfined compression test results showed that all samples tested exhibit a strain-softening behavior. The value of unconfined compressive strength increases with the increase of curing agent content and curing time but decreases with the increase of water content and modulus of SS. The optimal dosage combination is a sodium silicate modulus of 0.9, curing agent content of 12%, and curing time of 28d. SEM test confirmed the formation of gels in the treated soil sample, the dredged clay showed a more uniform and denser microstructure after treatment. Through XRD analysis, it is not easy to generate direct chemical reactions with no new mineral components generated in the sample. For high-water content dredged clay, it is recommended to use an optimum dosage combination of MK and SS to achieve a better treatment effect for use as construction fills.