Study On Physical Mechanical Properties And Pore Characteristics Of Foam Concrete

In recent years, the state promoted the energy-efficient construction, so that the construction of thermal insulation has become the key of the construction field. Building material insulation is an important part of energy saving and emission reduction. Foam concrete had a lot of advantages, such as:light weight, fire resistance, heat insulation and sound insulation. Not only can be poured in the construction site, but also produced a variety of components in the factory. Foam concrete was widely used in all kinds of buildings, especially the energy saving engineering.Foam concrete was prepared with chemical foaming method, hydrogen peroxide was the foaming agent, cement and fly ash was cementitious materials. Dry density of foam concrete was 600 kg/m3-1000 kg/m3. The pore structure of foamed concrete was test with image analysis method, the interaction and influence of the material composition, pore structure and properties were discussed, so as to optimize the performance of foam concrete.The results showed that the composition had a significant effect on the performance of the foamed concrete. The dry density was closely related to the performance of foamed concrete. When the hydrogen peroxide content was increased, dry density, compressive strength and thermal conductivity of foamed concrete was decreased, porosity was increased significantly. When the hydrogen peroxide content was decreased from 6% to 7%, the average compressive strength of foam concrete decreased by 31.5%?1.36MPa?. The relationship between compressive strength and dry density was conformed to the function y=1/?1.38889 - 0.00125x?, correlation coefficient is 0.911. The relationship between thermal conductivity and dry density was conformed to the function y= -7.709(e^x/2.189e7)+15.463, correlation coefficient is 0.956. The relationship between porosity and dry density was conformed to the function y=108.13 -0.05742x, correlation coefficient is 0.929.The composition has a great influence on the pore structure of foam concrete. The pore area ratio of foam concrete was decreased with the increase of hydrogen peroxide content and water binder ratio. When content of hydrogen peroxide was 7%, the water cement ratio was increased from 0.60 to 0.75, pore area ratio was increased from 40.1%to 49.5%. The distribution range of most probable aperture was increased obviously with the increase of hydrogen peroxide content. The proportion of large hole was increased and the proportion of small hole was reduced.There was a close connection between the pore structure and properties of foamed concrete. The relationship between compressive strength and pore area ratio was conformed to the function f= 12.65 - 0.15p, correlation coefficient is 0.941. When the pore area ratio was closed, the percentage of pore which pore roundness was 1.15-1.45 was increased, percentage of pore which pore roundness was more than 1.6 was reduced, compressive strength of foamed concrete was increased. When the most probable aperture was increased, the water absorption of foam concrete was obviously decreased. When the most probable roundness was increased, the percentage of pore which pore roundness was 1.15-1.35 was reduced, percentage of pore which pore roundness was more than 1.6 was increased, the water absorption of foamed concrete was increased. The relationship between thermal conductivity and pore area ratio was conformed to the function y= -0.0113 (x/e^32.272), correlation coefficient is0.9538. When the percentage of pore which aperture was 50-290um was increased, percentage of pore which pore roundness aperture was 290-530?m was reduced, thermal conductivity of foamed concrete was increased.Based on the Griffith fracture mechanics and composite materials theory, analyze and correct compressive strength, pore structure and mix of foam concrete. Build mathematical model which reveals strength, porosity, water-cement ratio and mean aperture of foam concrete.