Prediction of lightweight aggregate concrete compressive strength using ultrasonic pulse velocity test through gene expression programming

The use of lightweight structural concreteto reduce the weight of earthquake resistant buildings is very useful, and utilizing non-destructive tests for determining the concrete strength of these structures is essential.Ultrasonic pulse velocity test is one of the main methods of non-destructive testing in the assessment of compressive strength of concrete in the service area. The aim of this study is estimation of the compressive strength of lightweight aggregate concreteby offering suitable mathematical formulations.For this purpose, many samples of three different types of lightweight aggregate concrete are made and tested by concrete breaking machine and Ultrasonic pulse velocity instrument.Then some relationships for prediction of the compressive strength of the concrete by using ultrasonic test results are presented. Two different methods of fitting exponential function and Gene Expression Programming (GEP) are utilized to find the proper relationships. The results show that the exponential function has high accuracy in estimating the compressive strength of lightweight aggregate concrete made ​​with natural pumices. But it doesn’t have good results for concrete made of expanded clay. However the GEP has high accuracy for all the materials and the experimental results are perfectly compatible with the test results.