Several factors affecting the strength and deformation characteristics of cement-mixed gravel

Abstract

Related to the construction of a new type bridge abutment having the backfill of cement-mixed gravel, effects of moulding water content, w i, compaction energy level, cement-to-gravel ratio by weight, c/g, and curing period on the stress-strain behaviour of compacted cement-mixed gravel and their correlations were investigated. A series of drained triaxial compression tests were performed on a well-graded gravel of crushed sandstone from a quarry mixed with ordinary Portland cement. Possible effects of inherent anisotropy produced by compaction in different directions were evaluated to a limited extent. The following results were obtained. With a fixed c/g, the maximum compressive strength is attained when compacted at wi = the optimum water content, wopt, for a given compaction energy level, while the compressive strength is not an unique function of compacted dry density of solid, ρd (or compacted void ratio, e). These trends of behaviour are analysed in terms of positive effects of higher ρd (or lower e) of cement-mixed gravel and an associated increase in the cement amount per total volume for a fixed c/g as well as effects of the amount and strength of cement paste, both being a function of moulding water content. The benefits of compaction at wi = wopt for a fixed compaction energy level in achieving higher compressive strengths increase with an increase in c/g and the curing period. The pre-peak stress-strain behaviour tends to become more linear with curing period. The effects of inherent anisotropy are not as significant as those with air-pluviated unbound sand.