Experimental Study On Dynamic Mechanical Properties And Durability Of Recycled Concrete Under Low Temperature Environment

Since the reform and opening,the construction industry has been a pillar industry of our country,as the city’s construction and development vigorously,tens of thousands of construction waste to increase,from old building demolition of construction waste,not only occupy a large number of urban space and land resources,but also bring about air pollution,with the state advocates green economy and sustainable development strategy,how to deal with the city construction waste has become a problem to be solved.Recycling concrete waste into treasure for people to use,not only solve the construction waste occupied land space problem,but also can save natural sand and other raw materials resources,both economic and environmental protection.Based on the research background of recycled concrete in alpine areas,this paper summarizes the research status of recycled concrete at home and abroad,conducts the casting test with partial or total replacement of recycled aggregate,and conducts the experimental study on the macroscopic mechanical properties and microscopic durability of recycled concrete.The research results of this paper are as follows:(1)Mix ratio of recycled concrete was determined through experiments,test blocks were prepared,and mechanical experiments were carried out on recycled concrete.The results show that the compressive strength reaches its maximum when the water-cement ratio is 0.35 and the replacement rate is 0%.With the increase of fiber content,it enhances the toughness of concrete,and thus improves the strength of concrete.(2)Load test was conducted on recycled concrete at low temperature.The results showed that the compressive strength at different loading rates increased with the decrease of temperature,and the compressive strength at 25℃ was lower than that at-20℃.The compressive strength was significantly affected by temperature.The reason is that the test block is subjected to the coupling action of many factors at low temperature,which reduces the temperature,makes the water in the intervoids of the concrete test block freeze,and enhances the compression strength of the prism.(3)The durability of recycled concrete was studied.The results showed that with the increase of freeze-thaw cycles,the loss rate of compressive strength of recycled concrete with a replacement rate of 0% gradually increased.When the replacement rate is 100%,the increase of compressive strength loss rate is more than 40%.The loss rate of compressive strength is greatly affected by the replacement rate.