Experimental Study on the Flexural Fatigue Performance of Geopolymeric Recycled Aggregate Concrete

Geopolymeric recycled aggregate concrete (GRAC) has been treated as an environmentally friendly construction material by recycling construction and demolition waste and utilizing sustainable binders. For the first time, the flexural fatigue performance of GRAC based on fly ash/ground granulated blast furnace slag was studied, in which three slag contents (i.e., 0%, 15%, and 40% of the mass of the total binder) was employed. GRAC specimens with 100x100x400 mm3 were prepared, and tested under different stress levels and the constantamplitude cyclic loading conditions. Based on the results, the fatigue life, fatigue strength, and damage process of GRAC were analyzed and also compared with that of geopolymeric natural aggregate concrete. The results show the fatigue life distributions of GRAC were in good agreement with the two-parameter Weibull distribution. Furthermore, the fatigue equation based on a double logarithmic relationship was determined for the flexural fatigue strength of GRAC corresponding to different survival probabilities. It was revealed that the flexural fatigue strength of GRAC was decreased after the recycled aggregate replacement but was improved after the slag incorporation. Also, the fatigue flexural strengths at two million cycles at 95% survival probability were 0.577-0.708 of its static flexural strength, which is identical to ultra-high performance concrete.