Evaluation of macro- and meso-mechanical properties of concrete under the aggressiveness of landfill leachate

Current researches on the mechanical properties of concrete are mainly concentrated on the aggressiveness of sulfate, chloride ion, acid and freeze–thaw cycles. However, the evolution of concrete mechanical properties aggressived by landfill leachate remains to be revealed. As the micro-nano indentation test is a new method to measure the fine/micro mechanical behavior of materials, it is used in this research to evaluate the micro-mechanics of the landfill leachate of the concrete sample surface and different aggressived depths. In addition, the evolution of the macro-mechanical properties of concrete aggressived by the landfill leachate was studied through uniaxial compression tests. The results show that the hydration products with high elastic modulus are consumed by the aggressiveness of landfill leachate, which results in a large number of microscopic cracks on the surface of the concrete. Moreover, the longer the aggressive time, the shallower the aggressive depth, and the more severe the deterioration of the micromechanical properties of the sample surface. It is also notable that the uniaxial compressive strength of the concrete samples aggressived by landfill leachate showed a linear increase and then gradually decrease. Comparing with the sodium chloride and sodium sulfate solutions, the landfill leachate has the most significant weakening effect on the elastic modulus of concrete.