Study On Preparation Of Noise Reduction Material Of Highway Noise Barriers By Sludge Aggregate

Reducing the influence of traffic noise on daily life has been the main goal in construction and design of highway. Highway that has been built and is building has begun to use sound barricade as a method of reducing traffic noise. However,the materials are bad to environment,cost much and have low durability.This article is based on programs for science and technology development of transport department in Hubei province "research on using silt sludge aggregates to produce sound barricade in speedway".Investigate the Composition of sludge,the producing technique and performance of aggregate was studied,raise the idea of using baking sludge light aggregate to produce sound-barricading.Through research on mechanism of action of sound barricade and combined with characters of sludge aggregate,the design of sound-barricading production was raised.Theory of sound wave of transmission in tubule was under deep investigation, combined with dense-packing structural characters of aggregate,model between sound-absorbing frequency and aggregate particle size was established:according to analysis on transmission through in tubule,the smallest radius related to sound-absorbing peak was calculated.Cement-based materials are porous structure with aggregates'co-connection.Supposed that aggregates are the same radius, the area of hole between aggregates can be calculated according to particle size of aggregate and close-packing structure. When particle size is comparatively small,the hole can be seen as round hole.Therefore,the radius can be approximatively calculated. Since hole in materials are connected, it can be supposed that these holes are cylindrical tubule. Finally,the calculated radius is the radius during transmitting and theoretic relationship among aggregate radius,tubule radius and sound-absorbing peak rate has been established.According to this theory, the area of aggregate grain size of porous materials was fixed.As noise rate frequency in highway is concentrated in 800-1200Hz,relative aggregate gradation is 1.18-2.36mm and the average sound-absorbing coefficient is as high as 0.94.Through comparision of sound-absorbing performance,strength and durability between noise-reducing material made by sludge aggregate and present expansion of pearl rock,possibility of production of noise-reducing materials from sludge aggregate has been fixed.The factors impacting the noise-reducing performance of sludge aggregate have been investigated.The investigation mainly focused on principle of influence of mix proportion(water to cement ratio and gradation),material thickness,gradient structure design and back cavity on noise-reducing performance,which is combined with the relative usability of materials.The comparative reasonable design of sound barricade of sludge light aggregate has been raised,and this sound barricade support the construction of HangRui highway meeting the requirements of Two-oriented Society in Wuhan City Circle.