Research on composite damage of recycled concrete by the combined action of freeze-thaw and sulfate attack
For the damage of recycled concrete with different substitution rates under the coupled action of freeze-thaw cycles and sulfate attack,the rapid freezing method was used to test recycled concrete with 0,30％,50％and 100％of recycled coarse aggregate replacement rates.The mass loss,relative dynamic elastic modulus and cubic compressive strength of concrete were tested in the experiment and the microstructure and erosion products of concrete were analyzed by means of electron microscope and X-ray diffraction.The test results show that the recycled coarse aggregate has a great influence on the durability of concrete.With the increase of the replacement rate,the performance of recycled concrete gradually decreases with the increase of the number of freeze-thaw cycles.Sulfate slows down the deterioration of concrete to a certain extent,and freeze-thaw cycle is the main reason for concrete deterioration.Therefore,the damage mechanism under the combined action of salt heave and frost heave,hydrostatic pressure and chemical corrosion is proposed.
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