IMPROVING THE FATIGUE PERFORMANCE OF CONCRETE CONTAINING RECYCLED CONCRETE AGGREGATES USING BLENDED CEMENTS

摘要

The paper examines the potential of Metakaolin (MK) and Silica Fume (SF) blended with Portland Cement (PC) and Fly Ash (FA) in improving the flexural fatigue performance of concrete in which 100% Coarse Natural Aggregates (NA) has been replaced by Coarse Recycled Concrete Aggregates (RCA). The fatigue life data of different concrete mixes was obtained by performing flexural fatigue tests on approximately 128 beam specimens under four-point loading. In total, 96 static flexural tests were also conducted to facilitate fatigue testing. The fatigue performance of concrete containing RCA was assessed by estimating the variation in the fatigue tests data using Weibull distribution, design fatigue lives, theoretic fatigue lives etc. It has been seen that there is considerable reduction in the fatigue performance of concrete made with RCA compared to concrete containing NA. The use of blended cements such as MK and SF in combination with PC and FA has been found to significantly enhance the fatigue performance of concrete containing RCA. Also to predict the flexural fatigue strength of concrete made with RCA, the materials coefficients of fatigue strength prediction models have been estimated. The S-N-Pf curves have also been generated from the fatigue test data for all the concrete mixes. These models can be used to predict the flexural fatigue strength of concrete made with RCA and MK and SF. Further, the two million cycles endurance limits have been estimated for all the concrete mixes.