Setting time and compressive strength prediction model of concrete by nondestructive ultrasonic pulse velocity testing at early age

摘要

This study proposes a new model for estimating the setting and compressive strength development times, which involve changes in the concrete condition at early ages, using the ultrasonic pulse velocity testing. To this end, various effects, such as the effects of the water-to-cement (W/C) ratio, curing conditions (air-dry curing and curing at constant temperature and humidity), and aggregate, were experimentally examined to meet the specified concrete strength, i.e., 18-45 MPa. We found that varied as the W/C ratio of concrete decreased, which are affected by the hydration reaction, and that the ultrasonic pulse velocity was somewhat higher in concrete than in mortar. The samples cured under constant temperature and humidity exhibited a smaller error range than those that underwent air-dry curing. In addition, the relationships among parameters in different concrete samples were found to be linear during the initial and final setting periods and parabolic after the final set at early ages; subsequently, an exponential function prediction model was proposed for modeling the relationships. (C) 2020 Elsevier Ltd. All rights reserved.