Rheological and hardened properties of self-compacting concrete using hollow glass microspheres as a partial replacement of cement

Abstract

The main purpose of this research was focused mainly on the rheological influence of the “ball bearings” behavior of hollow glass microspheres (HGM), which affect the workability and stability of cementitious materials. They were used as partial replacement of cement on self-compacting concrete (SCC), in rates of 0% and 5%, promoting a possible reduction in the chemical admixtures consumption. The rheological properties were determined experimentally by direct tests using a rotational concrete rheometer and indirectly by empirical tests such as the slump flow, J-ring and L-box. From the data collected experimentally in direct tests, the behavior of mixtures was deeply analyzed by comparing the Bingham and the modified Bingham model, considering the influence of the plug flow. For this analysis, algorithms based mainly on the Reiner-Riwlin equations were developed with the purpose of showing in a simpler and more schematic way the iterative models applied in each case, contributing to the advancement of rheology of cement-based materials. In addition to rheological tests carried out, concrete properties in the hardened state were also measured at 28 days of curing. Young's modulus, Poisson's ratio, compressive strength, tensile strength, bending strength and chloride migration coefficient in a non-steady state were measured. The experimental results indicate that HGM incorporation improved the properties in the fresh state and slightly reduced the hardened properties of the SCC mixtures.