Preparation And Properties Of Recycled Dry Mixed Mortar From Construction Waste

With the rapid development of modern urban construction in China,a large amount of construction waste has been produced while natural building materials were consumed excessively,which has caused serious pollution to the ecological environment.The enhancement of people’s awareness of environmental protection and the proposal of national sustainable development strategy made the rational utilization of construction waste become one of the important tasks of scientific research units and construction enterprises.In the past,experts and scholars have made a lot of achievements in the research of recycled coarse aggregate from construction waste,however,the research of recycled fine aggregate is very little,which reduces the utilization rate of construction waste.Based on the fact that the utilization technology of recycled fine aggregate is mature abroad and it is still in its infancy in China,recycled fine aggregate produced by crushing waste clay brick and waste concrete were studied in this research.Natural sand were replaced by 0%,20%,40%,50%,60%,80% and 100% of recycled fine aggregate respectively to prepare recycled dry mixed mortar with four strength grades including M5,M7.5,M10 and M15.The apparent density,consistency,water retention,compressive strength and frost resistance of recycled dry mixed mortar were investigated.Results showed that the water requirement of the two types recycled dry mixed mortars increased with the increase of recycled fine aggregate content;the apparent density of those two types recycled dry mixed mortar is less than that of ordinary one prepared by natural sand;the water-retaining property was different for those two types recycled dry mixed mortar;for the mortar produced by waste clay brick,the compressive strength varies regularly with the amount of waste clay brick aggregate,nevertheless,it had no obvious change for mortar produced by waste concrete;the frost resistance of those two kinds of recycled dry mixed mortar all met the standard.The compressive strength of ordinary dry mixed mortar masonry,brick aggregate mortar masonry and concrete recycled fine aggregate mortar masonry were proportional to the mortar strength.The higher the mortar strength,the higher compressive strength of the hollow brick masonry.The measured compressive strength of recycled mortar porous brick masonry is slightly greater than the calculated average value,and the compressive strength of recycled mortar porous brick masonry is safe.