The assessment of concrete subjected to compressive and flexural preloading using nondestructive testing methods, correlation between concrete strength and combined method (SonReb)

Abstract

The objective of the research study is to investigate the influence of stress conditions on Non-destructive testing (NDT) methods. The experimental campaign was conducted on the aged concrete using both destructive tests (DT) and non-destructive tests (NDT) simultaneously. Two type of concrete were prepared, the first with 350 kg/m3 cement dosage, and the second with 400 kg/m3 cement dosage. The samples were tested unloaded and loaded at 20 %, 40 %, 60 %, and 80 % of the maximum compressive or flexural strength to predict these mechanical properties of concrete. The NDT tests were applied on concrete cubes to study the effect of a compressive load, while for a flexural load; reinforced and unreinforced concrete beams were formed and tested in different zones (compressed, tensioned, and neutral axis). The results of this study indicate that the stress conditions affect the NDT results, it was found that the reduction in RN and UPV of concrete subjected to 80 % compressive load was 9.4 % and 8.1 % respectively, while when subjected to 80 % flexural load the reduction was 2.5 % and 1.4 %. In addition, the results show a good relationship between the destructive test and the non-destructive test obtained by UPV and RN.