Experimental and numerical investigation of flexural behavior of cemented granular materials

This study aims to characterize both experimentally and numerically the flexural behavior of two different locally sourced granular materials stabilized with 3% general purpose (GP) cement. The four-point bending test was conducted on the compacted cement-stabilized beam specimens at various curing ages ranging from 7 to 90 days. The obtained experimental results elucidated both an exponential relation between curing period and flexural strength and a logarithmic relation between ultrasonic pulse velocity (UPV) and flexural strength for the cemented granular materials (CGMs) tested in this study. It was found that the rate of gain in flexural strength during the first 28 days is distinctly higher than that of during the subsequent 62 days. Taking into consideration the practical aspects of road operation, it is proposed that the flexural properties of CGMs, such as flexural strength, should be determined at 28 days curing age for use in pavement structural designs. In conjunction with the experimental study, a three-dimensional finite-element model of a four-point bending specimen was developed to simulate the flexural behavior of CGMs under static monotonic loading. The microplane model M7 was then implemented using commercially available software, and its parameters were calibrated (only two parameters of the model M7 were adjusted from their reference value) using the experimental flexural stress-strain response of CGMs at a 7-day curing age. The calibrated model M7 was then used to predict the flexural behavior of both CGMs at 28 and 90 day curing ages. Numerical simulations using the calibrated model M7 were shown to agree well with the flexural behavior of CGMs in experiments. This shows the capability of the calibrated microplane model M7 in simulating the flexural behavior of CGMs at various curing ages using minimum constitutive parameters.