Interface behavior of tensioned bars embedded in cement-soil mixtures

The overall performance of reinforced cement-stabilized soils depends significantly on the interface bond mechanisms that develop between the reinforcement and the surrounding cement-soil mixture. A laboratory experimental investigation based on uniform design theory was carried out to characterize the interface behavior of deformed bars embedded in cement-admixed soils. The study focused on the influence of cement content, water content and curing duration on the interface response. The interface bond strength of reinforced cement-soil mixture, as measured in pullout tests, was found to be proportional to the strength of cement-soil matrix, as obtained from unconfined compression tests. A simplified trilinear bond-slip model was developed as part of this study, which when properly calibrated was found to be capable of characterizing the bar-mixture interface shear response. Correlations were obtained to relate the interface bond strength with the three influence factors investigated in this study. The trends obtained on the influence of each factor on the interface bond resistance provided insights that were suitable to guide current design and construction practice of reinforced cement-soil mixture. The results and testing protocols presented in this study facilitated the understanding for interface shear mechanism between deformed bar and cement-soil mixture, and are expected to provide adequate means to satisfy the current lack of bar-mixture interface bond parameters in design specification for reinforced soil mixing structures.