Analysis And Experimental Research On Dynamic Mechanical Properties Of Phase-changing Energy-storing Concrete

Preparation of phase-changing energy-storing concrete with phase change materials in concrete.Because of its better energy storage capacity and high energy utilization rate,it has received more and more extensive attention.In this paper,phase-changing energy-storing aggregate is used by the expanded perlite as material adsorption of the butyl stearate.Surface modification with limestone powder,and then the phase-changing energy-storing aggregate and silica fume are added to the concrete to prepare the phase-changing energy-storing concrete.The dynamic compressive tests were performed with different contents of phase-changing energy-storing aggregates(equal volume of sand 0%,5%,10%,15%and 20%)and different content of silica fume(equal weight instead of 0%,5%,10%and 15%of cement)in concrete.The dynamic compressive tests of concrete after different freeze-thaw cycles(1,3,6,9,12and 15)on the basis of the selected group and the contrast group.In addition,different contents of polypropylene fiber and basalt fiber were added on the basis of the best dosage group.Dynamic compressive and splitting tests were performed on fiber reinforced concrete specimens,and the test results were analyzed.The experimental results show that the phase-changing energy-storing concrete can reduce the dynamic compressive strength of concrete,and the reduction range is less than 10%.Mixing silica fume in concrete can enhance its dynamic compressive strength,and the overall trend is increasing first and then decreasing,and the optimum content was 10%-15%.According to the influence trend of phase-changing energy-storing aggregate and silica fume,combined with the energy storage characteristics of phase-changing energy-storing concrete,when silica fume and phase-changing energy-storing aggregate are all 15%,the dynamic compressive strength is better,and the heat storage ability is better.The freeze-thaw cycles of phase-changing energy-storing concrete will reduce the density of specimens.The greater the number of freeze-thaw cycles,the smaller the wave velocity of the specimens,and the fastest decline is 1-3 times.The dynamic compressive strength of the phase-changing energy-storing concrete gradually decreases with the increase of the number of freeze-thaw cycles.The dynamic compressive strength of plain concrete freeze-thaw cycles 15 times is decreased by29%compared with the 1 time,when phase-changing energy-storing aggregate quantity is 15%,the dynamic compressive strength decreased by 20.5%,when silica fume admixture of 15%,the dynamic compressive strength decreased by 14%,when the content of both is 15%,the dynamic compressive strength decreased by 19.7%.Silica fume and phase-changing energy-storing aggregate incorporation will weaken freeze-thaw cycles damage on the dynamic compressive strength of phase-changing energy-storing concrete.However,when the both proportion of silica fume and phase-changing energy-storing aggregate is 15%,the trend of the dynamic compressive strength of the freeze-thaw cycles is higher than that of the silica fume contents is 15%.The addition of polypropylene fiber and basalt fiber can enhance the dynamic compressive strength of concrete,and the overall performance is increased first and then decreasing,and the better content is 1.5kg/m~3.The addition of polypropylene fiber and basalt fiber can enhance the dynamic splitting strength of concrete.It shows a trend of first increase and then decrease,and the best content of polypropylene fiber is1.5kg/m~3.The best content of basalt fiber is 1.8Kg/m~3.The addition of polypropylene fiber and basalt fiber can enhance the compressive and splitting toughness of concrete.The better toughness of polypropylene fiber is 1.5kg/m~3,and the better content of basalt fiber toughness is 1.5-1.8kg/m~3.Polypropylene fiber and basalt fiber have similar enhancement of dynamic compressive strength and dynamic splitting strength of concrete.The dynamic compression and dynamic splitting strength of the optimal dosage is about 5-10%higher than that of 0.6kg/m~3.However,the toughness of concrete is increased greatly.The dynamic compression toughness and splitting toughness of the optimal dosage are about 15-20%higher than that of 0.6kg/m~3.