Comparison of ultrasonic wave reflection method and maturity method in evaluating early-age compressive strength of mortar

This paper focuses on the comparison between the ultrasonic wave reflection method and the widely known maturity method in their ability to evaluate compressive strength development of portland cement mortars. The experiments were conducted under laboratory conditions on cement mortars with different water-cement ratios (0.35, 0.5, 0.6) cured under different isothermal and non-isothermal conditions (15 degrees C, 25 degrees C, 35 degrees C, 15-35 degrees C). The results show that the application of the maturity method for accurate strength estimation requires the knowledge of the limiting strength of the mixture for the specific curing condition that is considered. It is not sufficient to base this estimation on the values of the limiting strength obtained from the calibration tests. The relationship between reflection loss and compressive strength was found to be independent of curing temperature. This finding is an important step towards establishing the wave reflection method as a non-destructive method for estimating early-age strength in cement-based materials. (C) 2006 Elsevier Ltd. All rights reserved.