Experiment And Analysis On Mechanical And Thermal Properties And Stability Of Phase Change Cycle For Phase Change Concrete

Incorporation of phase change materials in concrete to make phase change concrete,which can improve energy storage performance and energy efficiency,reduce energy consumption of building and other advantages,has attracted more and more attention.But phase change concrete also has low strength,phase change cycles stability and other problems.In this paper,active carbon was used to absorb the butyl stearate to make active carbon energy storage aggregate,and incorporation it to concrete to make phase change concrete.Make the basic mechanical properties,thermal conductivity,heat storage and phase change cycles stability test and analyses the test results of phase change concrete with different time of phase change cycles(0 time,30 times,60 times),different content of active carbon energy storage aggregate(0%,10%,15%,20%,25%).The test of basic mechanical properties shows that:With the content of active carbon energy storage aggregate has increased,the mechanical properties of phase change concrete is reduced greatly.When the content is not greater than 15%,the compressive strength and splitting tensile strength of phase change concrete will reduced less than 10%,the flexural strength reduced less than 13%.Temperature has small affect to basic mechanical properties of the phase change concrete.When room temperature is in 30? and 10?,the difference of compressive and tensile strength of phase change concrete is less than 2%,the bending strength is less than 4%.Failure section of phase change concrete shows that the active carbon energy storage aggregate is distributed evenly in the concrete,and the packaging is good,but its bond with the concrete is poor,and affects the mechanical properties of the concrete.The test of thermal conductivity show that:The thermal conductivity of phase change concrete increased with the increase of active carbon energy storage aggregate content,when the content exceeds 15%,the thermal conductivity increases more than 25%,to ensure the insulation capacity,mixing amount of active carbon energy storage aggregate should be less than 15%.The room temperature higher,the thermal conductivity of the phase change concrete bigger.The content of active carbon energy storage aggregate is 15%;the difference of thermal conductivity for phase change concrete at room temperature 30? and 10? is less than 4%.The test of heat storage and release show that:Through the melting and solidification of internal phase change material,phase change concrete can store and release heat,the heat storage capacity increases with content of carbon energy storage aggregate.When the content of active carbon energy storage aggregate is 15%,the fluctuation amplitude of center temperature 100mm×100mm× 100mm block decreases 1?.At the temperature above the melting point,the phase change concrete surface will appear grease due to the phase change material melt,grease will not disappear when the phase change material solidification,and grease quantity and content of active carbon energy storage aggregate is positively correlated.The test of phase change cycles show that:Property of active carbon energy storage aggregate is stability,in the course of phase change cycles physicochemical properties did not changed.Its influence on the concrete mechanical properties and thermal properties not changed significantly with phase change cycles.Phase change concrete is stability at phase change cycles.Due to the evaporation of water the density and thermal conductivity of phase change concrete will reduced in the phase change cycles,and with the increasing times of phase change cycles,reduce of the density and thermal conductivity become slowly.Without the influence for age of concrete,the basic mechanical properties of phase change concrete did not change significantly during the phase change cycles,and the change of basic mechanical properties was less than 4%after 60 cycles.