Research on concrete compressive strength in existing reinforced concrete elements with Schmidt hammer, ultrasonic pulse velocity method and destructive testing of cores

Abstract

Concrete is a widely used material in construction. Quality control, maintenance and extending its service life are major issues after the construction stage and during the service of reinforced concrete buildings and facilities. This article presents the author’s experimental results for determining the compressive strength of concrete for tests on 12 reinforced concrete beams at the age of concrete 1926th day. In previous studies, some of the beams were loaded to a stage corresponding to the yield strength of the longitudinal tensile reinforcement, and others to a loading stage before yield, reaching a maximum crack width of 0.3 mm. The reinforced concrete elements were kept indoors for two years, and for the next more than three years they were left outdoors, exposed to external atmospheric influences. In the research was used combination of non-destructive and partially destructive techniques. The compressive strength of the concrete was determined using the method of elastic rebound (Schmidt hammer), ultrasonic pulse velocity method and partially destructive techniques - core sampling. The relative errors in the values of compressive strength obtained by the different methods were calculated. A comparative analysis of the experimentally obtained results by different methods was made. The tests were performed according to European standards for non-destructive and destructive testing of reinforced concrete structures.