Curing effects on strength, small strain stiffness, and microstructure of a lime-treated lean clay

This paper presents a multi-scale investigation of curing effect on the strength, stiffness, and microstructure of a lime-treated decomposed red mudstone (LDRM). Particular emphasis was assigned to develop a unified framework characterizing the development of the strength and small strain stiffness with curing period. Uniaxial compression tests and bender element tests were conducted on LDRM compacted at three void ratios and two lime contents up to 8640 h (360 days) of curing. Three-stage behavior, namely, initial curing, primary curing, and secondary curing was clearly identified, from which a power model was proposed to capture the S-shape evolution curve. The separation between three stages were clearly identified by examining the inflection point on the S-shape curve and the tangent at the inflection point. The proposed model applied well to not only LDRM, but also to a range of artificial soils. Changes in the pore size distribution and microfabric of LDRM during long-term curing were confirmed by mercury intrusion porosimetry and scanning electron microscope analyses. In detail, the progressive agglomeration and the transition in pore volume were considered as the structural interplay responsible for the increase in strength and small strain stiffness of LDRM.