Rebound testing of cylindrical spun-cast concrete elements

Abstract

The aim of the research was to determine the relationship between the Schmidt N rebound index and the compressive strength of spun-cast concrete elements with low water-cement (w/c) ratio. In the research 22 specimens of 8 different mixtures were tested. The investigated mixture parameters included w/c ratio, compaction intensity and type of aggregate. The compressive strength of the concrete in the outer, middle and inner region of the spun-cast element and of the vibrated cube were assessed by testing drilled cores after non-destructive testing of the specimens. Statistical regression functions have been defined for the determination of the relationship between the rebound index and the compressive strength. A special new method has been developed for the quality control of spun-cast concrete elements using a rebound hammer.