| In order to improve the engineering properties of soft soils, materials, such as cement and fiber, can be introduced to the soil mass. Currently, design criterion for a cement-soil mixture requires only the measurement of unconfined compressive strength. This simple measurement may not be adequate to describe the behavior that results from differing field loading conditions. A series of consolidation tests and unconfined compression tests were conducted with special attention being paid to the effects of curing time and vertical curing stress. It is shown that the introduction of cement into soft soils results in decreased compressibility and increased unconfined compressive strength when compared to unimproved soils. Also, the unconfined compressive strength of the cement-soil mixture increases with curing time and with vertical confining stress. The existence of fiber in the cement-soil mixture can significantly improve its ductility in the post-peak strength zone without significantly changing the unconfined compressive strength. The stiffness of the mixture can be increases when the mixture is cured under vertical confining stress, compared with the mixture without curing stress. Strength gain over curing time is modeled and a general unconfined compressive strength prediction equation is developed. |
