Effect Of Pore Features Of Autoclaved Aerated Concrete On Thermal Conductivity

With the improvement of living standard,the energy consumption is higher and higher.Building energy saving is imminent.The production of clay brick not only wastes energy,but also makes environmental pollution.China is now promoting new building materials to reduce energy consumption and pollution.Under this background,the porous characteristics of autoclaved aerated concrete brings excellent heat preservation and sound insulation.It can improve the indoor environment comfort effectively.It will bring theoretical and practical application value to establish the relationship between pore features and thermal conductivity.In this paper,different density autoclaved aerated concrete(B04,B05,B06 FA and B06AAC)are made and their thermal conductivity are measured.The results shows that with decrease of density,the porosity increases,the thermal conductivity decreases and the thermal conductivity decrease.And under the same density,the thermal conductivity of the fly ash aerated concrete is lower than that of the sand aerated concrete.Considering the influence of aperture on the thermal conductivity of autoclaved aerated concrete,aperture are change by controlling foam stabilizer,mixing time of aluminum power paste and blowing agent without changing the mixture ratio and density.The results shows that the aperture decreased with the increase of foam stabilizer and mixing time of aluminum power paste.And aluminum power also can decrease the aperture.According to measure the thermal conductivity of the autoclaved aerated concrete,the result shows that thermal conductivity increase with the increase of aperture.The porosity and thermal conductivity are measured to provide finite element modeling data and material properties.Determine the technique according to compare the SEM and XRD of matrix.The images of autoclaved aerated concrete block section are binary conversion to gather statistics about aperture and number of pore.Based on Monte Carlo method,create the pore center coordinates by using MATLAB and import ANSYS for modeling and meshing.In order to keep in line with the experiment,the finite element model adopts the same loading method as the experiment.The finite element model is proved to be available by comparing thermal conductivity and aperture distribution of numerical simulation and experiment.The advantage of the finite element model is that it can simulate the working conditions that the experiment conditions are hard to meet.So the influence of the porosity and aperture of the autoclaved aerated concrete on the thermal conductivity is simulated by the finite element model.The result shows that the simulation results are similar to the experiment results.With the increase of porosity,the thermal conductivity decreases,and the thermal conductivity increases with the increase of the aperture.In this paper,a mathematical model of porosity and thermal conductivity of autoclaved aerated concrete and a mathematical model of aperture and thermal conductivity are established through comparing experiment data,numerical simulation data and thermal conductivity prediction model of porous medium.