Study On The Relationship Between Flow Resistance And Sound Absorption Performance Of Ceramsite Sound Absorbing Materials

With the development of rail transit,the noise pollution brought by it has also attracted people's attention.In recent years,ceramsite concrete sound absorbing materials have been used to control such pollution,such as ceramsite concrete subway track sound absorbing panels,near rail suction.Sound wall and so on.However,how to further improve the sound absorption performance of ceramsite sound absorbing materials to maximize the utilization of materials has become the key to the upgrading of such products.The literature shows that flow resistance is one of the important parameters for evaluating the sound absorption performance of sound absorbing materials,but the relationship between the flow resistance and sound absorption properties of this sound absorbing material has not been studied.This research innovatively designed the instrument for measuring the flow resistance of ceramsite concrete materials-flow resistance meter,used to measure the flow resistance of ceramsite sound absorbing materials,and studied the relationship between flow resistance and sound absorption performance through a large number of experimental data.The main research results are as follows:(1)In this paper,a flow resistance meter with simple operation and controllable flow rate is developed.The instrument consists of an electric vacuum pump,a high-precision flow meter,a high-sensitivity valve,a high-resolution differential pressure gauge,and a special test piece platform.Reliability analysis of the measured data by F-value test and t-value test shows that the accidental error and system error of the device meet the accuracy requirements.(2)The flow resistance of ceramsite concrete is directly related to its void ratio.The smaller the void ratio,the larger the flow resistance.Adding fine ceramsite,latex powder,polypropylene fiber and increasing water-cement ratio will increase the flow resistivity.Among them,the water-cement ratio is the most obvious,the influence of latex powder is second,the effect of polypropylene fiber is smaller than that of latex powder,and the addition of fine ceramsite in ceramsite sound absorbing material has the least influence,and the flow resistance rate is 3545 Pa.s./m~2 is increased by 12.5%to 3990 Pa.s/m~2.(3)The particle size of ceramsite has a significant effect on flow resistance.Among them,for ceramsite concrete with only one aggregate particle size,the flow resistivity decreases as the particle size increases.The ceramsite concrete with various particle sizes has a flow resistance ratio between ceramsite concrete with only one aggregate particle size.The ceramsite concrete with the particle size of 1~3mm aggregate has the largest flow resistance rate,the ceramsite concrete with the particle size of 3~5mm is the second,and the ceramsite concrete with the particle size of 5~8mm aggregate has the smallest flow resistance.However,the sound absorption performance of ceramsite is not completely negatively correlated with its flow resistance rate,and the test pieces with three kinds of ceramsite mixed at a ratio of 6:14:44 have the best sound absorption performance,and the flow resistance is 3029 Pa.s/m~2,which is between 1 and 3 mm.Between the pieces and the 3~5mm ceramsite test piece.The above results show that the sound absorption performance of ceramsite concrete does not decrease with the decrease of flow resistance,but has an optimum flow resistance range.Below or above this range will reduce the sound absorption performance of ceramsite concrete.(4)Based on the experimental data of the flow resistivity and the average sound absorption coefficient,the fitting equation is established by the LM-UGO algorithm of1stOpt software.The fitting curve plotted according to the fitting equation shows that the average sound absorption coefficient increases with the increase of the flow resistance rate when the flow resistance is low,and reaches the peak when the flow resistance is 3095Pa.s/m~2.The peak of the sound absorption coefficient is 47.48,and the average sound absorption coefficient decreases with the increase of the flow resistance rate after the peak value.The parametric analysis shows that the LM-UGO algorithm has achieved good results in fitting the average sound absorption coefficient.The applicability test of the equation shows that the fitting equation has high applicability.