A Study on Measurement and Calculation Method for Coefficient of Linear Thermal Expansion of Low-Quality Aggregate

Abstract

In order to reduce the environmental impact, it will be important to make effective use of low-quality coarse aggregate to the extent that it satisfies the performance requirements of concrete. However, there are physical properties such as drying shrinkage and thermal expansion that cannot be captured by routine quality tests of coarse aggregate. In order to determine the drying shrinkage and thermal expansion coefficient of coarse aggregate, the authors have previously proposed a method to determine the length variation characteristics by directly attaching strain gauges to the coarse aggregate particles. In this study, we measured the temperature strain of low-quality coarse aggregate particles using strain gauges, which has not been clarified so far, and also investigated the method for calculating the coefficient of linear thermal expansion. As a result, it was clarified that even low-quality coarse aggregate particles can be measured by strain gauges to determine the temperature strain. It was also revealed that the coefficient of thermal expansion of low-quality coarse aggregate particles is not much different from that of normal-quality coarse aggregate particles, with no significant difference. Furthermore, it was found that the coefficient of linear thermal expansion of coarse aggregate particles can be roughly determined by using the test report attached to a commercially available strain gage. The calculated coefficient of thermal expansion of coarse aggregate particles by this method differs by a maximum of ±1 μ/°C from the exact coefficient of linear thermal expansion referring to quartz glass.