Study On The Performance Of Recycled Concrete Powder For Wet Mixing Mortar

In the rapid development of China’s construction industry,along with a large amount of construction waste generated in the construction waste transportation and recycling process,inevitably produce a large number of recycled concrete powder,if not its research and utilization not only waste resources,but also serious pollution surroundings.Based on the surface roughness of recycled concrete powder from construction waste,the porosity is high and the water demand is high.Contains unhydrated mineral components and a large number of potentially active SiO2.In this paper,recycled concrete powder as admixture for wet mix mortar.The main study of wet mortar based on the ratio.And after determining the basic mix,The influence of the content of fine powder of recycled concrete,the content of fly ash and the type and content of admixture on the consistency,water retention,shrinkage and strength of wet-mixed mortar.At the same time,microscopic analysis of different dosage of re-concrete powder and chemically-induced wet-mixed mortar was carried out.Experimental research and theoretical analysis are as follows:First,the ratio of mortar to cement was 1:4,the ratio of water to cement was 0.7,the content of recycled concrete powder was 10%,the content of fly ash was 20%,Cellulose ether content 0.04%,Water reducer dosage 0.6%.Under this mixture ratio,the consistency of wet-mixed mortar is 74mm,the water retention 91.8%,the shrinkage 0.08%,the compressive strength at 7d reaches 11.4MPa,the strength at 28d reaches 14.6MPa and the strength grade meets M10 ordinary wet-mix mortar.Second,as the content of recycled concrete powder increases,the water retention of wet-mixed mortar gradually increases and the shrinkage rate decreases.When the content of recycled concrete powder is 30%,the shrinkage rate of 28 days is reduced by 37.3%compared with the blank.However,the consistency of wet-mixed mortar tends to decrease.The recycled concrete powder has a great influence on the compressive strength of wet-mixed mortar.When its content is 10%,the 3d intensity is 3.1%higher than that of blank group,,Mixed with more than 20%of recycled concrete powder mortar significantly lower than the benchmark intensity.Third,fly ash and recycled concrete powder complex mixed as a mineral admixture preparation of wet mixed mortar,both play a complementary role,with the increase of fly ash content,the consistency of wet mixed mortar is on the rise and in the amount of When more than 20%,the compressive strength of wet-mixed mortar first increases and then decreases.When the content of fly ash is 30%,the compressive strength of wet-mixed mortar is the highest at 28 days.Fourthly,the microstructure studies show that when the content of recycled concrete powder is 10%,there are more ettringite in the system,the strength in the early stage is higher than that in the blank group,but the strength is not good in the late stage.When the content is 30%Products significantly reduced,the structure is more loose.