Study on the properties of anorthite-based porous sound-absorbing materials prepared by steel slag and fly ash

Abstract

The efficient utilization of solid wastes, such as fly ash and steel slag, has attracted significant attention across the globe. In this paper, these two kinds of waste materials are used to prepare porous sound-absorbing materials, so as to achieve efficient resource utilization and environmental protection, and promote green manufacturing and circular economy. In this study, steel slag and high-alumina fly ash were used as the primary raw materials to prepare green bodies via organic foam impregnation. Subsequently, a high-temperature sintering process was implemented to get the porous sound absorption material product from the green bodies. The effects of several factors, including the ratio of steel slag and fly ash, sintering temperature, and pore structure, on the sound absorption and mechanical properties of the product were investigated. Based on the anorthite region in the CaO–Al2O3–SiO2 ternary phase diagram region, the composition ratio of the material was designed. The composition and microstructure of the material were characterized by X-ray diffraction and scanning electron microscopy. From the results, with the increase of the ratio of fly ash and steel slag, the composition of low melting point substances in the system decreases, and the amount of liquid phase decreases, which weakens the pore blocking phenomenon inside the material, resulting in the increase of pore size and noise reduction coefficient of the material. Besides, higher sintering temperature tends to correlate to greater density and higher compressive and flexural strengths but lower porosity, and the sound absorption coefficient demonstrated a peak with respect to sintering temperature. Furthermore, when the reduction of polyurethane sponge body pore size was taken into account, the product's sound absorption coefficient also showed a peak. The optimal parameters for our porous materials are as follows: fly ash:steel slag = 48 : 25, polyurethane sponge pore size = 40 ppi, sintering temperature = 1160 °C at 1-h duration (bulk density = 573.98 kg/m3), compressive strength = 1 MPa, porosity = 79.35 %, and noise reduction coefficient = 0.47.