Strengthening And Microstructure Analysis Of Stable Recycled Aggregate For Construction Demolition And Waste

With the advancement of urbanization,the demolition of old buildings will generate some construction waste,which will cause huge pollution to the environment and waste of resources.This article intends to use the recycled aggregate obtained after the construction solid waste treatment in the water-stable crushed stone mixture for the pavement base construction.A series of strengthening methods were used to analyze the performance changes of the recycled coarse aggregate before and after strengthening,and basic mechanical experiments and micro analysis were performed on the mixture.Finally,the optimal blending ratio of recycled coarse aggregates for engineering and the reason for the strength change of water-stable recycled aggregates are explained through microscopic experiments.First of all,the feasibility of the study was determined by referring to various relevant domestic and foreign literatures,and the content of the study was formulated to pick out the classified construction waste,namely recycled concrete and recycled brick aggregate.The basic physical properties were measured,and compared with the natural aggregate,it was found that the water absorption of the recycled aggregate was higher than that of the natural aggregate,the crushing value was larger than that of the natural aggregate,and the overall property was poor,so it needed to be strengthened.Reinforced coarse aggregate was strengthened under different conditions using a Los Angeles abrasion meter,water glass solution,and titanate coupling agent to obtain the best strengthening effect of each of the three strengthening methods.Strengthening method,the best strengthening method is comprehensively obtained,that is,water glass solution strengthening,the strengthening concentration is 8%,and the strengthening time is 5 hours.The optimal moisture content and maximum dry density of cement stabilized recycled aggregate with different content of recycled coarse aggregate were determined by compaction experiments.Basic mechanical experiments were carried out after forming the specimen.At 4%cement dosage,as the amount of recycled coarse aggregate increases,the unconfined compressive strength,splitting strength,and compressive rebound modulus of the mixture increase first and then decrease.However,when the cement dose becomes 5%and the content of recycled coarse aggregate increases,the above three mechanical performance indexes all show a downward trend.Scanning electron microscopy was used to observe the microstructure of the mixture.It was found that the interface structure between the recycled aggregate and the cement slurry was much more complicated than that of the natural aggregate.There are macadam,brick aggregate and old mortar respectively combined with new cement slurry interface.Moreover,the composition of hydrate in the interface was further understood through energy spectrum analysis.