Research On Wear Resistance Of New Type Of Recycled Permeable Concrete Under Sulfate Attack

In order to alleviate the problem of urban waterlogging,permeable concrete pavements have been extensively studied.The new type of recycled permeable concrete breaks through the limitations of traditional permeable concrete,and at the same time alleviates the pollution of construction waste,which has important research value.However,there are currently few studies on new recycled permeable concrete.Therefore,in order to strengthen its theoretical support and promote engineering applications,this article studied the abrasion resistance,sulfate attack resistance and abrasion resistance after sulfate attack of new recycled permeable concrete.The specific contents of the study are as follows:（1）By pre-setting steel bars of different diameters and pulling them out after initial setting,new permeable concrete with different pore diameters were prepared,and the influence of pore diameter and porosity on the wear resistance,compressive strength and water permeability coefficient of the new permeable concrete was studied.The results showed that the porosity of the new permeable concrete has a good linear relationship with the water permeability coefficient,and there is an exponential relationship with the compressive strength.The abrasion resistance is negatively related to the pore size,but the increase in the pore size does not significantly weaken the wear resistance.The recommended pore size range is 2-3 mm,the water permeability coefficient is 3.41-7.52 mm/s,the compressive strength conforms to C40,and the amount of wear per unit area is less than 3.5 kg/m².（2）Medium and low-quality recycled aggregates（RCA₁ and RCA₂）were used to replace natural aggregates（NA）with different substitution rates to prepare new permeable concrete.The compressive strength and abrasion resistance were tested to study the influence of recycled aggregate quality and content on the performance.The results showed that as the quality of recycled aggregate deteriorates and the amount increases,the compressive strength and abrasion resistance of the new type of permeable concrete also decrease,and the extent of the decrease increases with the decrease in quality.The quality and content of recycled aggregate affect its abrasion resistance mainly on the internal abrasion resistance of the specimen,and the impact on the surface abrasion resistance is not significant.The optimal content of RCA₁ and RCA₂ is 25%,and the abrasion resistance is not much different from that of the specimens made of natural aggregate.（3）A 60-time sulfate dry-wet cycle test was carried out on the new recycled permeable concrete with different quality and content to study the effect of the quality and content of recycled coarse aggregate on its sulfate corrosion resistance.The results show that as the number of wet and dry cycle increases,the quality and compressive strength of each sample increase first and then decrease.With the decrease in aggregate quality or the increase in aggregate content,the peak value is earlier.The increase in the content of recycled aggregate has a weakening effect on its sulfate resistance,but the performance of RAC₁ is not significantly reduced at 25%.（4）In order to study the influence of recycled coarse aggregate quality and content on the abrasion resistance of new type of recycled permeable concrete after sulfate erosion,the above specimens were subjected to 30 and 60 sulphate dry-wet cycles,and the amount of wear per unit area in the first 30 and last 40 wear turns after sulphate erosion was measured.The results showed that sulfate attack has less influence on the abrasion resistance of the surface layer than the internal abrasion resistance.As the number of dry-wet cycle increases,the abrasion resistance deteriorated more severely,and the deterioration of the quality and the increase of the content aggravated this deterioration.After 60 dry-wet cycles,the wear resistance of RAC₁ with 50%recycled aggregate content and RAC₂ with 25%recycled aggregate content still meets the requirements.In summary,it is feasible to prepare a new type of permeable concrete with good abrasion resistance,sulfate resistance,water permeability and mechanical properties from a suitable amount of recycled aggregates of different qualities,and its application has high environmental significance.