STRENGTH AND DEFORMATION PROPERTIES OF COMPACTED CEMENT-MIXED GRAVEL EVALUATED BY TRIAXIAL COMPRESSION TESTS

摘要

To achieve as possible as a high cost-effective construction of important civil engineering structures, such as bridge abutments, using cement-mixed gravel (CMG) for the backfill, a series of drained triaxial compression (TC) tests were performed on CMG specimens. Two types of well-graded gravels were used. Axial and lateral strains were measured locally on the lateral surface of solid cylindrical specimens. It was found that, for a same cement to gravel ratio by weight, the peak strength q_(max) tends to become the maximum when compacted at the optimum water content, w_(opt), for a given compaction energy level. This trend is due largely to the smallest compacted void ratio and partly due to the largest cement content per unit volume associated with the maximum dry density. The other influencing factors include an incidental optimum combination of strength and amount of cement paste that may be attained when compacted at w = w_(opt). The relationship between the ratio of "q_(max) at a certain molding water content, w" to "q_(max) at w_(opt), q_(maxOMC)." and the normalized deviation ratio of w from "w_(opt), | w- w_(opt)| /w_(opt)" is rather unique whether compacted at dry or wet of optimum, for different compaction energies and for the two types of gravel. It is also shown that the initial Young's modulus tends to become the maximum when compacted at w_(opt) while the pre-peak stiffness and post-peak ductility generally increase with an increase in the molding water content. Based on the test results, it is recommended to compact a given type of cement-mixed gravel around at w_(opt), ensuring that the compaction is not made dry of optimum for a given compaction energy.