泡沫混凝土气孔结构数学表征及其分析

Mathematical Description and Analysis on Characteristics of Pore Structure for Foam Concrete

为分析泡沫混凝土孔结构表征参数之间的关系和气孔结构特点,建立了紧密堆积模型和非紧密堆积模型,基于不同的理论模型推导了孔结构主要参数包括孔隙率、气孔内表面积、气孔壁厚度的计算公式,分析各参数之间的关系;通过实测泡沫混凝土的孔结构参数,验证了计算公式的可行性,并将计算公式应用于泡沫混凝土孔结构特征分析.研究结果表明:当容重等级小于1 000 kg/m3时,泡沫混凝土形成的气孔结构为紧密堆积型结构,气孔壁厚计算结果与统计结果偏差在12%以内,验证了紧密堆积型结构计算公式的可行性;当容重等级大于或等于1 000 kg/m3时,泡沫混凝土形成的气孔结构为非紧密堆积型结构,气孔壁厚计算结果与统计结果偏差在3%以内,验证了非紧密堆积型结构计算公式的可行性;在相同容重下,气孔壁厚度随气孔直径的增大而增大,随孔隙率的增大而减小;1 m3泡沫混凝土的气孔内表面积可达到3 000 m2以上,气孔壁厚可低至60μm以下,泡沫混凝土具有多孔薄壁、小体积物料与大体积的气孔空气共存于一体、小体积物料以巨大的面积暴露在气孔的气体之中的结构特征.

To analyse the characteristics of the pore structure of foam concrete and reveal the relationships between various pore structure parameters, dense and non-dense packing structure models were established. A formula for the calculation of pore structure parameters, including porosity, surface area, and pore wall thickness, was derived based on various theoretical models to analyse the relationships between these parameters. The formula was validated using the measured pore structure parameters and used to analyse the characteristics of the pore structure of foam concrete. The results show that the foam concrete has a dense packing structure when the dry density grade is less than 1 000 kg/m^3. The difference in the pore wall thickness according to the experimental data and that obtained via the dense packing structure model is less than 12%, which illustrates that the dense packing structure model is feasible. When the dry density grade was egual or greater than 1 000 kg/m^3 foam concrete has a non-dense packing structure. The difference in the pore wall thickness according to experimental data and that obtained via the dense packing structure model is less than 3%, which verifies the feasibility of the non-dense packing structure model. Pore wall thickness increased with increasing pore diameter, and decreased with increasing porosity for the same bulk density. The pore surface area can be over 3 000 m2 per m^3 of foam concrete and the pore wall thickness can be as small as 60μm. Foam concrete is characterized by a porous structure with thin walls, the coexistence of materials with small volumes and pores with large volumes, and the exposure of materials with small volumes to the gas in pores with a large areas.