Study on performance of recycled aggregate permeable concrete based on freeze-thaw cycles of different media
The properties of recycled aggregate permeable concrete under different media freeze-thaw cycles were systematically studied.By preparing different proportions of recycled aggregate permeable concrete specimens and performing freeze-thaw cycling experiments in different media such as water,brine and deionized water,the effects of freeze-thaw cycling on the mass loss rate,relative dynamic e-lastic modulus,residual compressive strength,continuous porosity and permeability coefficient of concrete were investigated.The results showed that after 120 freeze-thaw cycles,the quality damage rate of the two groups of specimens was close to the maximum value.In the saline environment,the compressive strength loss was faster,and the strength decreased to 75％after 60 cycles.The continuous porosity and water permeability of the saline group were higher,with a porosity of 27.1％and a permeability coefficient of 4.4％after 70 cy-cles.Scanning electron microscopy and XRD analysis showed that the chemical erosion was significant in the early stage of salt freezing,and the expansion material filled the micro-cracks.The physical erosion worsened the freeze-thaw damage in the later stage,which showed that the water permeability increased rapidly and then increased slowly,and the strength gradually decreased,which provided an experimental reference for optimizing the anti-freezing performance of salt.
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