Using ultrasound to monitor stiffening process of concrete with admixtures

A nondestructive one-sided wave reflection factor (WRF) test was applied to concrete with a variety of admixtures, including an accelerator silica fum e as replacement, a high-range water-reducing admixture, and a retarder The results are presented herein. The WRF test is sensitive to the presence of admixtures. In addition to WRF tests, dynamic modulus tests were performed on normal- and high-strength concretes. The results from these tests are c orrelated with the results from the WRF tests. A new objective method for d etermining the time of occurrence of critical points on the WRF curve was d eveloped. The critical WRF points were found to correlate well with critica l points in set time and cement hydration processes.