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

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/m³. 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/m³ 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 diame- ter, and decreased with increasing porosity for the same bulk density. The pore surface area can be over 3 000 m² per m³ of foam concrete and the pore wall thickness can be as small as 60 μm. 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.