Probability of failure of RCA concrete with ternary blended cements

Abstract

The paper presents the results of an investigation carried out to examine the flexural fatigue strength and failure probability of concrete made with 50% Coarse Recycled Concrete Aggregates (RCA) and ternary blended cements using Silica Fume (SF) and Metakaolin (MK). A control mix containing 100% Coarse Natural Aggregates (NA) was also tested for comparing the flexural fatigue results. A total of 128 concrete beam specimens were tested under flexural fatigue using 100 kN MTS Servo-controlled actuator under four-point flexural fatigue loads applied at frequency of 10 Hz. The material coefficients of various fatigue test models have been calculated to predict the flexural fatigue strength of different concrete mixes. The S-N-Pf curves have been generated for all the concrete mixes using the experimental fatigue data at various probabilities of failure. Two million cycles endurance limit has also been calculated for all the concrete mixes to assess the flexural fatigue strength of concrete made with 50% RCA. A minute decrease occurs in the endurance limit of concrete made with 50% RCA (i.e. 56% of average static flexural strength) with respect to the control concrete (i.e. 58%). Whereas, the endurance limits of 66% and 68% have been observed for the concretes made with 50% RCA with SF and 50% RCA with MK respectively. Therefore, the use of SF and MK has been found to enhance the flexural fatigue performance of concrete made with RCA.