Study On The Relationship Between Pore Structure And Property Of Super Light Foam Cement Insulation Board

Ultra-light foamed cement insulating material is a kind of porous material, and pore structure in a large extent determines the mechanical properties and heat-conducting property of this type of materials. To characterize microstructure of foamed cement and study its influence on the properties of the material is of importance for the material development and application of super light foamed cement insulating board.In this paper, chemical foaming was used to prepare the super light foamed cement insulation board in the bulk density of 100~180kg/m3. the effect of the type of cements, water-to-cement ratio, foam stabilizing agent, hydrogen peroxide dosage on pore structure was investiagted. The Image Pro Plus image software was used to characterize the parameters of pore structure, porosity, pore size, pore size distribution and the relationship between pore wall thickness and compressive strength and thermal conductivity were established. Pore structure model was established by using C++ programming software and Fluent thermal analysis software was used to simulate the steady state flat method measuring thermal conductivity conditions. Heat flow inside the foam cement the motion propagation regularity was observed and in-depth study of the cement foam insulation board insulation and heat insulation mechanism.1?Water-to-cement ratio and type of cements have a significant influence on the gel pore, and the effect of stability of foam agent and hydrogen peroxide dosage on air void is more obvious. Gel pore size distribution in the 4~10 nm, the pore volume with water to cement ratio increases and decreases with increase of sulphoaluminate cement cement. When the dosage of hydrogen peroxide is 6.5 ~7.5%, the air voids are relatively small and uniformly distributed, and most air voids have a size of 0.5 ~1mm. When the dosage of hydrogen peroxide is 8.0~9.0%, the air voids become larger and trend to be open to each other, and most air voids have a size of 2.0 ~3.0 mm.2?With increasing porosity of super light foamed cement insulating board, dry density decreases proportionally, while compressive strength and thermal conductivity decrease exponentially. For the bulk density of the super light foamed cement thermal insulation board 120kg/m3, in order to protect the appropriate strength and has a low thermal conductivity, the aperture should be controlled within the range of 1.355~1.711 mm.3?In the numerical model, the air voids were set to be spheres and the structure was constructed using sphere packing algorithm. The numerical model gave a simulated thermal conductivity coefficient agreeing well with the experimental results, and the difference was less than 2.7~11.2%. For two-dimensional model of transient thermal analysis, the main way of heat transfer in foamed cement is though the wall of air voids, and porosity and pore wall thickness is the dominant factors affecting the effective thermal conductivity, the minimum pore wall thickness should be controlled within the range of 0.10~0.18 mm. The air void size has very small effect on the thermal conductivity coefficient. Parameterized modeling through computer simulation technology and computed the equivalent thermal conductivity can provide certain theoretical support in the espect of studying internal heat conduction and temperature distribution of foamed cement.