The Research Of Green Environmental Protection Cement-based Haydite Sound Absorbing Material

With the rapid development of modern society, noise pollution is more and more serious, social research deepening of sound-absorbing materials. Haydite get more people`s attention because of it `s good sound-absorbing function. Using haydite made of porous sound-absorbing material has the quality of light 、 sound absorption performance、durability、 good fire prevention advantages, conform to the requirements of the traffic lanes especially the urban subway, so more and more get the favour of staff.In this paper, we study the sound-absorbing material with haydite and cement as main raw materials, adding polypropylene fiber and additive etc, through mixing, stirring, pressing and maintenance, etc. The whole research process including the choice of raw materials, formulate mixture ratio, analyzing the sound absorption performance of the material、 mechanical properties、durability and fire prevention performance, further adjusting and optimizing the mixture ratio, guarantee the porous sound-absorbing material light weight, volume density between 1200 ~ 1400 kg/m3; Guarantee the materials meet the requirements of high-performance sound-absorbing material, and noise reduction coefficient(NRC) to achieve national Ⅱlevel standard, meaning 0.6≤NRC≤0.8; Ensure the materials meet the requirements of the rail plate bearing: 28 day`s compressive strength greater than 8.0 MPa,28 day`s flexural strength greater than 2.0 MPa; Ensure durability, fire retardancy of materials to achieve the relevant state standard. To achieve the above goals, mainly includingthe following research:(1) Selection of raw materials: by coMParing and ceramsite physical performance test, choose low bulk density, low bibulous rate, high strength of the cylinder as the sound-absorbing material.(2)Research materials mixture ratio, By controlling the density and strength index of the sound-absorbing material, adjust the ceramsite, cement, water, fiber, water reducing agent dosage, the formation of the initial mixture is ceramsite dosage is 65% ~ 60%, cement of 35% ~ 40%, water cement ratio 0.19, water reducing agent is 1.2%, fiber content is 0.3%, according to material made of the mixture density within 1220 ~ 1430 kg/m3, 7 day`s compressive strength within 7.4 ~ 11.3 MPa.(3) Research material mechanics performance, on the basis of initial mix proportion, through the test analysis ceramsite and cement particle size grading, label, parameters such as dosage of fiber and cement,further control the density and intensity index, adjust the ceramsite grain size and grading, and optimizing the mixture ratio, further sound-absorbing material mix proportion optimization. coMPared with the 60% dosage of ceramsite ceramsite(Coarse ceramsite and the proportion of fine ceramsite is 30:70~ 50:50), keep Material dosage and other parameters same, can be made into the material density of about 1300 kg/m3, the 7 d compressive strength value at about 9 MPa.(4) Research materials sound absorption performance, get the sound absorption coefficient of materials by standing wave tube method, analysis of ceramsite grain size, material density, thickness, the influence of fiber content on the sound absorption coefficient. After testing found, the greater of the density, the decreased of the absorption coefficient, but the low frequency sound absorption coefficient increase slightly; the greater of the thickness,the absorption coefficient has increased, and low frequency sound absorption coefficient increased more obvious; When coarse ceramsite grain size is 6 ~ 8 mm, fine ceramsite grain size is 2 ~ 4 mm, material density between 1200 ~ 1300 kg/m3, thickness is 100 mm, fiber content to the maximum extent at near 0.3% increasing material absorption coefficient. After test, Sound-absorbing materials belong to high performance sound-absorbing materials, noise reduction coefficient(NRC) up to the national level of sound absorption performance standard: Ⅱ(NRC)≥0.6. Using circular tube theory analysis of the factors influence on the sound absorption performance of materials, and coMParing the test results are consistent.(5) Test using sound-absorbing material performance, including the freezing-thawing performance and fireproof performance, After 200 freeze-thaw cycles, the quality of the material loss rate was 3.7%, the relative dynamic elastic modulus at 82.4%, satisfy with the requirements of freeze-thaw resistance, through burning test, mass loss is △m=9.4%, less than the specification 50%;Average temperature in the furnace △T=6℃, less than standard 30 ℃; Sample continue to burn time t=0, meet the requirements; total combustion value PCS = 0.47, below the standed 2.0; So the combustion performance of sound-absorbing material level A1, satisfies the requirement of metro sound-absorbing materials on the properties of fire.