Non-destructive evaluation of strength gain of ordinary portland cement mortar by ultrasonic pulse velocity method

Abstract

This research is based on the results of the study of ultrasonic pulse velocity and compressive strength of ordinary Portland cement mortar. Objectives of this study are to determine correlations between ultrasonic pulse velocity and compressive strength of cement mortar and to predict strength of cement mortar at 28 days within 02 days using ultrasonic pulse velocity of cement mortar. Ten samples of ordinary Portland cement obtained from ten different sources were used to prepare thirty (30) specimens of cement mortar. Water/cement ratio, sand content, method of specimen preparation, curing conditions were kept constant throughout the experiment. Portable Ultrasonic Nondestructive Digital Indicating Tester with a transducer of 54 kHz frequency was used to measure ultrasonic pulse velocity. Initially ultrasonic pulse velocity of ten samples of cement mortar was measured and compressive strength of same specimens was determined. Then the behavior of ultrasonic pulse velocity with cement hydration was studied. Graphs between ultrasonic pulse velocity and compressive strength of cement mortar, and graphs between ultrasonic pulse velocity and curing time were plotted for ten samples. Correlations obtained from above experiments were used to predict 28 days compressive strength of cement mortar within 02 days. In this research it was found that the relationship between ultrasonic pulse velocity and compressive strength was linear and Lime Saturation Factor of cement also has an influence on this relationship. Further it was seen that, with the increase of curing period, ultrasonic pulse velocity of all samples increased. At the end it was possible to obtain an equation that can predict the cement strength and that equation was verified using another five (05) cement mortar samples.