Repeatability of the rebound surface hardness of concrete with alteration of concrete parameters.

Diagnostic of concrete structure properties is essential towards assessing the properties of the evaluated element. Since the Schmidt hammer is categorized as an economic and effective non-destructive testing tool, an extensive investigation is applied on several hundred of concrete specimens produced from several types, in order to assess the compressive strength and understand the limitations and boundaries of rebound hardness. From normally vibrated concrete to ultra-high strength concrete, water-binder ratio, water-powder ratio, supplementary cementitious materials and admixtures are relatively affecting the response of rebound index of the Schmidt hammer in terms of repeatability for compressive strength prediction. Additional porosity measurements were performed to enhance this statement. [ABSTRACT FROM AUTHOR]