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In this study, Young’s moduli ( E ) of 28-day concrete determined through destructive tests according to NBR 8522−2017 were compared with results of nondestructive tests, such as the ultrasonic pulse velocity (UPV) and impulse excitation technique (IET). Different batches of concrete were prepared by varying the following conditions: water/cement ratio (0.45, 0.55, and 0.65), basaltic aggregate type (originating from Foz do Iguaçu-PR, Toledo-PR, and Guarapuava-PR), and aggregate content (60 %, 54 %, 48 %, and 42 %). The results showed that the coarse aggregate source significantly influenced Young’s modulus more than the other factors. The dynamic Young’s moduli were higher by approximately 16 % for IET and 28 % for UPV. After curing for 28 days, the dynamic Young’s moduli determined at the flexural and longitudinal modes were statistically equal, although the longitudinal mode yielded lower deviations than flexural modes. An equation correlating the dynamic and static Young’s moduli was derived, considering the coarse aggregate density and content. The regression coefficient was 0.811–0.901, with a maximum error of 2.46 GPa. The proposed equation is useful for predicting the static Young’s modulus of concrete using dynamic modulus values obtained from nondestructive methods. Moreover, the proposed equation will improve Brazilian standard test methods, which are based on the natural frequency and UPV.
Thomaz et al. (Thu,) studied this question.