Effect of glass fiber and high temperature on the mechanical properties of recycled aggregate concrete

This research aimed to mainly study the mechanical properties of improved recycled aggregate concrete, through added glass fibers with high tensile strength and high temperature resistance, and then subjected to high temperature. The recycled coarse aggregate with maximum sizes at 19, 12.7, and 9.5 mm was composed of crushed concrete, tile, and brick. Three glass fiber dosages of 0.1%, 0.2%, and 0.3% of concrete volume were selected to prepare the concrete specimens for the testing of compressive strength, flexural strength, splitting tensile strength, and ultrasonic pulse velocity (UPV). Test results showed that the recycled aggregate concrete (RAC) with smaller maximum aggregate size (D_max) may increase the capillary pores inside the concrete, in turn reduce the UPV of the concrete. The compressive, flexural and splitting tensile strength of glass fiber-reinforced RAC may present higher strengths than that of the control concrete without glass fiber; these strengths increased with the increase in glass fiber to a limit dosage of 2%. For elevated temperature exposure, the RACs incorporating glass fiber may have better properties of mechanical strength and UPV than that of control concretes, while the properties were found to decrease with the increase in temperature.