An assessment of the progressive failure of concrete using pulse velocity measurements

摘要

The experimental findings of the ultrasonic pulse velocity (UPV) test on concrete cubes during progressive compressive loading are reported in this paper. The concrete cubes were prepared with two types of cement, namely, ordinary portland cement (grade 43) and portland slag cement and tested in progressive compression till failure, during which the pulse velocity was recorded at each increment of the load. The development of strength with age during curing was also monitored by measuring the pulse velocity. The pulse velocity measurements during the progressive loading revealed that the pulse velocity increases slightly during the initial stage of compression. Thereafter, the pulse velocity decreases due to the development of micro-cracks. It was also observed that cracking starts earlier for the higher strength concrete (low water-cement ratio), than the lower strength (higher water-cement ratio) concrete. This was evident from the decrease of pulse velocity earlier during the progressive compression testing. Abrupt reduction in pulse velocity occurred at 75-85 percent of the failure load. These facts demonstrate the usefulness of the UPV test for anticipating failure in concrete structures.