Assessment of reinforcement correction factor for concrete core testing

Abstract

In this study the reinforcement correction factor of concrete core testing was investigated in more detail to prepare appropriate outlines for the interpretation of results in order to minimise the uncertainties involved. For this purpose, an extensive experimental programme was undertaken, considering different concrete strength levels, moisture conditions, core size, length-to-diameter ratios of the core and steel bar size in various configurations. The effect of variations of these parameters on the ratio of average compressive strength of cores containing steel bars to that of corresponding plain specimens was probed. The results showed that the correction factor is highly dependent on the volume percentage and the position of reinforcing bars in the core, which are closely interrelated. The experimental results therefore did not show good agreement with the provisions of BS 6089 or the Concrete Society report on concrete core testing. Statistical analysis of the prediction of cube compressive strength using linear and non-linear regression models was thus conducted. The results showed that the regression models are feasible tools for predicting compressive strength on the basis of test results for cores containing steel bars, but the results of the non-linear equations were found to be more accurate than the results from linear models.