Factors affecting uniaxial compressive strength and ultrasonic pulse velocity of meso-scale heterogeneous concrete

Ultrasonic pulse velocity test (UPV) and uniaxial compressive strength (UCS) is widely used for building conversion model in concrete non-destructive test. However, the stability and accuracy of test results is always a questionable issue because concrete is heterogeneous on the meso-scale. In this study, a meso-scale simulation methodology aimed at specifying the influencing factors of UCS and UPV is proposed. Firstly, a meso-scale finite element model of concrete consisting of mortar, interfacial transition zone (ITZ) and randomly distributed aggregates is developed. Furtherly, by using L18 orthogonal array, the effects of significant influencing factors were analyzed: aggregate content, aggregate type, maximum aggregate size, thickness and porosity of ITZ, and water-cement ratio. The analysis of variance (ANOVA) results show water-cement ratio is the only significant influence of UCS. But significant factors for UPV including water-cement ratio, aggregate type and ITZ porosity. In addition, the rationality of the simulation methodology is validated with low relative errors (4.72% for UCS and 3.21% for UPV) is achieved on the experimental data and theoretical formulations.