Experimental Study Of Thermal Conductivity Of Light Recycled Concrete

The working performance and mechanical property of recycled concrete is worse than ordinary concrete because recycled aggregate has large discreteness,many angularity and high porosity,but they also have better thermal insulation performance.It can give full play to its advantages of low thermal conductivity and has important significance for saving resources and protecting environment by using recycled concrete in the block of building wall.Based on the replacement rate of recycled coarse aggregate which was 100%,this paper incorporated waste stone powder and ceramisite into recycled concrete.On the one hand,it can further improve the thermal insulation performance of wall material by itself;on the other hand,it can make the wall material lighter,reduce the amount of traditional cementing material,reduce pollution and cut the production costs.The block of light recycled concrete can realize the comprehensive benefit of green,energy saving,environmental protection and economic.This paper tested mechanical property and thermal conductivity of 18 groups of recycled concrete specimens by using the TY1-2000H compression testing machine and thermal conductivity meter of the heat flux method of HFM436/3/1E which was made by Netzsch.The main work and result was as follows:1.This paper studied the influence of mechanical property and thermal conductivity of recycled concrete by incorporating waste stone powder and fly ash respectively(the mixing amount is 0%?12%?24%)when using 100%recycled coarse aggregate to substitute natural coarse aggregate.The experimental results showed that,the compressive strength and thermal conductivity of recycled concrete were decreased,the thermal insulation performance was enhanced when incorporating waste stone powder.The compressive strength of recycled concrete was decreased after slightly increased and the thermal insulation performance was relatively stable when incorporating fly ash.2.Based on the total adding amount which was 24%,this paper studied the influence of mechanical property and thermal conductivity of recycled concrete by combined admixture of waste stone powder and fly ash(the proportion is 1:3,1:1,3:1),and proposed an optimal mixing rate according to the experimental results.The experimental results showed that,mechanical property and thermal conductivity of recycled concrete were relatively stable when recycled concrete mixed with waste stone powder and fly ash.The comprehensive effect was best when the mixing rate of waste stone powder and fly ash was 3:1.3.Based on above experimental results of waste stone powder and fly ash,this paper studied the influence of mechanical property and thermal conductivity of recycled concrete when using ceramisite to substitute coarse aggregate(0%?25%?50%?75%?100%)and pottery sand to substitute fine aggregate(0%?50%).The experimental results showed that,The compressive strength and thermal conductivity of recycled concrete were decreased,the thermal insulation performance was enhanced obviously when the content of ceramisite and pottery sand were increased.4.According to a large number of experimental results,this paper proposed a manufacture method of light recycled concrete that has lower production cost,reasonable strength and thermal conductivity(0.5956 W/(m·K))far less than ordinary concrete and general recycled concrete.