Considering The Size Effect Research On High Temperature Performance Of Recycled Concrete

With the sustainable development strategy put forward by the 1980 s,the maintenance and reasonable use of natural resources has been an important direction of human development.Recycled concrete technology has been considered to be the main measures to develop the ecological of green concrete and achieve the goal of sustainable development of building resources.More and more scholars to study the performance and application of recycled concrete,but in consideration of recycled concrete size effect and mechanical properties of recycled concrete of high temperature performance research is few.Study the mechanical properties of recycled concrete after high temperature,it is effective to improve the application of recycled concrete.In this paper,in order to better promote the development and application of recycled concrete,the compressive properties of recycled concrete after high temperature and size effect on the performance of recycled concrete compression are studied.The main contents are:First of all,the test process of recycled coarse aggregate,to get to the aggregate basic performance and recycled coarse aggregate grading.Compared with natural aggregate research found that recycled coarse aggregate on the apparent density increase 1.39%,on the packing density was reduced by 11.4%,on the crush index increased by 6.18%.Then,the high temperature properties of recycled concrete is researched.Through the recycled concrete of high temperature test can be found,with the increasing of temperature,recycled concrete specimens experienced a color change from light gray-brown-grey-black apparent process,quality gradually reduced.The mass loss from 20℃ to 400℃ is greater than that of temperature from 400℃ to 600℃.Similar to ordinary concrete,the compressive strength of recycled concrete decreases with the increase of temperature.Taking RC100 as an example,the temperature from room temperature to 200℃,the residual compressive strength decline rate is about 4.58%;the temperature from 200℃ to 400℃,the residual compressive strength decline rate is about 3.93%;the temperature from 400℃ to 600℃,the residual compressive strength decline rate is about 9.06%.It can be seen that with the increase of temperature,the residual compressive strength of recycled concrete is different,and the residual compressive strength of recycled concrete at 400℃ to 600℃ is the largestMoreover,study on the influence of recycled coarse aggregate replacement rate on the compressive strength of recycled concrete after high temperature.And study on the influence of recycled coarse aggregate replacement ratio on the compressive strength size effect of recycled aggregate concrete.The results show that:With the increase of recycled coarseaggregate replace rate,residual compressive strength of recycled concrete after high temperature gradually decreased.However,the increase of recycled coarse aggregate replacement rate has little effect on the compressive size effect of recycled concrete.Finally,the effect of compressive strength of recycled aggregate concrete was studied.The results show that:The size effect of recycled concrete compressive strength is more obvious.Length is 100 mm cube specimens and side length is 200 mm cube specimens,compared with the standard length is 150 mm cube specimens,the compressive strength of the size effect coefficient in(0.94 ~ 0.98)and(1.03 ~ 1.12),the averaged 0.96 and 1.08.Analyze the test data,obtained the 150 mm cube compressive strength and 100 mm cube compressive strength of the relevant relation.And also obtained the 150 mm cube compressive strength and 200 mm cube compressive strength of the relevant relation.