Performance Research And Analysis Of Recycled Aggregate Concrete For Construction Wastes

Under the big background of high-speed economic development in our country,urban construction has entered a peak period,on the one hand,there are a lot of old buildings of shanty town village demolition and renovation,in the series of activities will produce large amount of construction waste to processing;On the other hand,in the process of urbanization,the surrounding sandstone and other raw materials face the risk of depletion.According to the above mentioned problems,the reclamation of recycled aggregate can effectively solve the disposal of waste concrete and alleviate the ecological environmental problems caused by over-exploitation of resources.Therefore,research on the utilization of recycled aggregate concrete is in line with the sustainable development strategy of China,which is in line with economic and social benefits and has great significance in research.This paper firstly summarizes the development status of the utilization of construction waste at home and abroad,and then,on the basis of determining the experimental scheme of recycled aggregate concrete,the four kinds of recycled aggregates provided by the two cooperative construction waste recycling plants are selected as the basic research objects.First of all,by changing the dosage of watercement ratio of recycled aggregate and multiple sets of test and analysis of different water cement ratio conditions,the recycled aggregate replacement rate on apparent density of concrete and the influence of work performance.At the same time,the mechanical properties and durability of recycled aggregate concrete(including anticarbonization,dry shrinkage,frost resistance and anti-permeability)were analyzed.The results show that the apparent density of recycled concrete decreases with the incorporation of recycled aggregate.The types of recycled aggregates and water ash have a great influence on the performance of recycled concrete,and the variation law is very inconsistent.The incorporation of recycled aggregates can improve the slump,but it is more affected by the water-cement ratio and the aggregate type.The results of the mechanical test of recycled concrete show that when the high water-cement ratio,the incorporation of recycled aggregate has little effect on the compressive strength of the recycled concrete cube.The incorporation of recycled aggregate can improve the bending strength of recycled concrete.From the experimental data,the regenerated aggregate content is 40% to 70%,which is the optimal replacement rate range.The mixed recycled aggregates on the axial compressive strength of recycled concrete is affected,as a whole analysis test data,low water-cement ratio,the mixed recycled aggregates reduces the strength of recycled concrete,high water cement ratio,the strength of recycled concrete is enhanced.The results of durability test show that the anti-carbonization performance of recycled concrete is good,and the incorporation of recycled aggregate is beneficial to the carbonization performance of recycled concrete.As a whole,when the recycled aggregate is 100% substitute for natural aggregate,the dry shrinkage increases greatly,which is related to the structural characteristics of the recycled aggregate.However,the replacement of natural aggregate with recycled aggregate is beneficial to dry shrinkage,which is related to the strong water absorption of recycled aggregates.Although the antifreeze and thawing properties of different recycled aggregate concrete are very different,they can withstand more than 50 freeze-thaw cycles.According to the test data analysis,the recycled aggregate concrete can meet the requirements of anti-seepage performance index in ordinary concrete engineering.