Study On Physical Performance Of New Inorganic Sound-absorbing Material

The rise of urban metro rail transit brings convenience to people while noise pollution occur.Noise pollution as one of world's four major environmental pollution,which poses a serious threat to the life of buildings?people's physical health and mental state.The use of cement-based porous sound-absorbing material is one of effective ways to control noise pollution.However,traditional cement-based porous soundabsorbing material is not suitable for post-wall grouting.Therefore,new inorganic sound-absorbing material suitable for post-wall grouting was studied in this paper.The material has advantages such as high water-cement ratio and stone rate of 100%.The performance of the material was studied by physical tests.The main contents and conclusions show as follows:Sound absorption performance of new inorganic sound-absorbing material was studied by orthogonal test.Range and variance analysis show that expanded perlite content has very significant effect on average sound absorption coefficient and noise reduction coefficient;Water-cement ratio and polypropylene fibers content have a certain influence on average sound absorption coefficient,but have no effect on noise reduction coefficient;Foaming agent content has no effect on average sound absorption coefficient and noise reduction coefficient.Optimal ratio of new inorganic soundabsorbing material is sure that water-cement ratio 4.0,foaming agent content 0.2%,polypropylene fiber content 2.5%,expanded perlite content 25%.The average sound absorption coefficient and noise reduction coefficient under this combination are 0.36 and 0.35 respectively.Analysis of influencing factors on sound absorption performance of new inorganic sound-absorbing material was carried out.With the addition of thickness and cavity,the first resonant frequency moves to low frequency.When the thickness is 90 mm,average sound absorption coefficient and noise reduction coefficient are 0.37 and 0.35,respectively;Average sound absorption coefficient is 0.33 when the cavity is 50mm;The presence of moisture reduces the sound absorption performance.Average sound absorption coefficient and noise reduction coefficient of new inorganic soundabsorbing material are 0.37 and 0.35,which are higher 27.8% and 25.7%,respectively;Wedge structure can improve sound absorption performance effectively.Average sound absorption coefficient and noise reduction coefficient with single wedge structure are 0.45 and 0.47,which are higher 25% and 34.3% than that without wedge structure,respectively;Average sound absorption coefficient and noise reduction coefficient with double wedge structure are 0.50 and 0.53,which are higher 11.1% and 12.8% than that with single wedge structure,respectively.Mechanical performance of new inorganic sound-absorbing material is studied through orthogonal test.Range and variance analysis show that water-cement ratio has very significant effect on compressive strength and flexural strength of new inorganic sound-absorbing material.However,foaming agent content,polypropylene fibers content and expanded perlite content have no effect on compressive strength and flexural strength.With the increase of water-cement ratio,compressive strength and flexural strength of new inorganic sound-absorbing material decline sharply.Howeber,the strength is higher than undisturbed soil,so the material can be applied to post-wall grouting.The microstructure characteristics of three groups of new inorganic soundabsorbing material with different ratios were analyzied by electronic scanning microscope.SEM analysis shows that there are many pores interconnected pores and closed pores in new inorganic sound-absorbing material.The addition of polypropylene fibers increases the effective porosity of new inorganic sound-absorbing material and improves the sound absorption performance of new inorganic sound-absorbing material.The paper reveals that the sound-absorbing mechanism of new inorganic sound-absorbing material is mainly viscous action and heat conduction.The regular propagation and reflection of incident sound wave of new inorganic sound-absorbing material with different thickness and cavity were analied at the same time.The theory of acoustic attenuation was analied to reveal sound absorption mechanism of wedge absorbing structure.