粉煤灰免烧多孔保温陶粒的制备及孔结构调控研究

Preparation and Control of Pore Structure of Porous Insulating Ceramsite with Fly Ash

粉煤灰免烧多孔陶粒具有质轻、保温隔热、吸声降噪、制备工艺简单及可高效利用固废等特性,而其孔结构决定了多孔陶粒的性能。为了调控免烧多孔粉煤灰陶粒的孔结构,以膨胀珍珠岩为造孔剂、双氧水为发泡剂研制了免烧多孔粉煤灰陶粒,探索了养护制度、造孔剂掺量和发泡剂掺量对免烧多孔陶粒孔结构与性能的影响。结果表明:蒸压养护更有利于陶粒的水化反应;生陶粒在130℃下蒸压养护12 h后,会更有利于多孔结构的调控和强度的形成;膨胀珍珠岩和双氧水的掺入都会显著提高陶粒的孔隙率,当膨胀珍珠岩的掺量超过10%后,由于生成的水化硅酸钙堵塞孔结构,其孔隙率的提升不再明显;当双氧水的掺量超过7.5%后,由于孔结构的合并及坍塌,导致孔隙率变化不再明显;当膨胀珍珠岩掺量为10%、双氧水掺量为7.5%时,制备的陶粒总孔隙率为69.22%,导热系数为0.0931 W/(m·K)。

Sintering-free porous ceramsite with fly ash has attracted much attention because it features lightweight,excellent thermal insulation,sound absorption,simple preparation and efficient recycling of solid waste,whose properties are governed by its pore structure.In order to tailor the pore structure,sintering-free fly-ash ceramsite was successfully prepared by using expanded perlite as pore forming material and hydrogen peroxide as foaming agent.The influences of curing regime,expanded perlite dosage as well as hydrogen peroxide dosage on the microstructure and the properties of the obtained ceramsite were investigated,respectively.Results show that:autoclaved curing is more beneficial to the hydration reaction of ceramsite;after being cured for 12 h at the autoclave curing temperature of 130℃,a desired strength could be achieved for the subsequent pore structure tuning;both the introduction of expanded perlite and hydrogen peroxide can significantly increase the porosity of ceramsite.However,when the expanded perlite dosage exceeds 10%,the porosity will not increase significantly due to the blocking of the pores caused by the created calcium silicate hydrate;when the hydrogen peroxide dosage exceeds 7.5%,the increase of porosity is no longer obvious due to the integration and collapse of the pores.For the ceramsite obtained with the optimal expanded perlite dosage of 10%and the optimal hydrogen peroxide dosage of 7.5%,the total porosity and thermal conductivity are 69.22%and 0.0931 W/(m·K)respectively.