One-sided stress wave velocity measurement in concrete

Measurement of the velocity of stress waves in concrete provides valuable information on the state of the material. Recently, a number of papers have been published on wave velocity measurements in concrete when access to only one surface of the structure is possible, such as for the case of concrete pavements. In this paper, the existing one-sided methods for stress wave measurement in concrete are reviewed. Then, a modified method for one-sided stress wave velocity determination in concrete is introduced; the novel aspect of the modified technique is the data collection and processing system, which more accurately determines the arrival of the generated longitudinal and surface waves. The modified method, which is demonstrated on a variety of materials including steel, PMMA, and concretes of varying composition, is shown to be superior to existing one-sided techniques. Using the developed technique, the significant effect of the moisture content gradient within concrete on one-sided velocity measurements is demonstrated. Finally, one-sided velocity measurements are shown to be useful for monitoring the strength gain of early age concrete.