Concrete Compressive Strength Estimation by Means of Nondestructive Testing: A Case Study

Abstract

Estimation of the mechanical properties of concrete in an existing structure is possible with the results of surface hardness and ultrasound tests (nondestructive tests (NDTs)). For both the use of correlation curves is necessary, it is established between NDT and the results of the compressive strength of test specimens or extracted from structure. The objective of this study is to produce correlations between the results of surface hardness and ultrasound NDTs and the compressive strength of the structural concrete in the bleachers of a soccer stadium in the city of Cianorte, which is located in the northwest part of the state of Paraná, Brazil. This concrete structure, which is approximately 26 years old, has some defects, such as corrosion, concrete segregation and cracks. Concrete spalling in one of the slabs has recently raised some concern. Another significant issue is the absence of records regarding concreting of the bleachers’ structure. Therefore, mapping the reinforcement was initially performed according to the results of a surface hardness test, as recommended by standard [1]. An ultrasound test was simultaneously performed according to standard [2] for the same points employed in the surface hardness test. The concrete specimens were extracted according to the recommendations of standard [1] to determine compressive strength, perform the NDT and construct the correlation curves for the results. A total of 26 concrete specimens were obtained from all structures of the bleachers. From the methodology and the results of the study, highly reliable equations were obtained from the correlation curves among the compressive strength of the concrete specimens and the values of the surface hardness index and the ultrasound wave propagation velocity.