Properties of modified concrete with crumb rubber: Effect of the incorporation of hollow glass microspheres

Abstract

In this study, the effect of incorporating hollow glass microspheres (HGM) on the mechanical properties of modified concrete with CR (crumb rubber) was evaluated. Different concrete samples replacing 15% of fine aggregates (total weight of CR + HGM = 15%) were prepared. It was found that the increase in the microsphere content was directly proportional to the slump, compressive strength, and the modulus of elasticity. The increase in the microsphere content was inversely proportional to density. Additionally, we found that in the modified concrete, the width, height and the number of cracks increased as the HGM content increases. The combined sample HGM12.5-CR2.5 (the one with the highest content of microspheres) resulted in concrete with the highest compressive strength of 19.1 MPa, which is 243% stronger than the concrete with only crumb rubber (9.2 MPa). From the XRD results, we were able to detect the presence of different phases formed by hydration during the process of preparing concrete mixtures. The micrographs allowed identifying the fracture in the microspheres during the preparation of the concrete mixtures when they came into contact with the aggregates. The addition of hollow glass microspheres to the mixtures prepared from crumb rubber improved their mechanical properties, and this makes it a potential system that can replace the traditional materials in the production of concrete.