Effect of coarse aggregate on acoustoelastic effect in concrete

Abstract

The acoustoelastic technique exhibits substantial potential for in-situ stress measurement in concrete. However, concrete, being a complex multiphase material, is subject to various influencing factors on its acoustoelastic properties, encompassing material strength, aggregate size, porosity, temperature, and humidity. A comprehensive understanding of how these factors influence the acoustoelastic characteristics of concrete is imperative for the advancement of acoustoelastic technology in engineering applications. This study concentrates specifically on the coarse aggregate of concrete, a crucial component forming the material's skeleton, and investigates the influence of its placement and size on acoustoelastic coefficient (AEC) of concrete. 25 two-dimensional mesoscale finite element models with varied maximum aggregate diameters were established to explore the influence of aggregates and excitation frequency on acoustoelastic effect in concrete. To streamline calculations, the equivalent elastic constant method was proposed to simulate the acoustoelastic effect in concrete. AECs for all models were determined using the stretching technique. The results indicate that the AEC of concrete tends to rise with increasing ultrasonic excitation frequency. Moreover, both the particle size and placement of aggregates have limited impact on acoustoelastic effect of P-waves in concrete. To substantiate this conclusion, empirical tests were conducted on 15 concrete prism specimens, featuring five distinct aggregate gradations. The experimental outcomes aligned with the numerical predictions, corroborating the findings.