Thermal Conductivity And Mechanical Performances Of Foam Concrete Under The Effects Of Bubble Structure

With the vigorous promotion of prefabricated buildings by the country,foam concrete has been widely used in prefabricated buildings due to its light weight and good thermal insulation properties.However,due to the relatively weak mechanical properties of foam concrete,it cannot meet certain specific strength requirements.It is precisely because of this that the scope of use of foam concrete is limited.At the same time,the testing process of compressive strength and thermal conductivity of foamed concrete has been nearly perfect,but the research on the specific changes of the two processes at the micro level is relatively lacking,and clarifying the micro change process is an important part of explaining and improving the macro performance.This article starts from improving the mechanical properties of foam concrete and exploring the specific changes in heat transfer and pressure.The research is carried out through experiments and simulations.The main contents are as follows:(1)Under the influence of a single factor,the strength growth of foamed concrete is not obvious and the best effect under a single condition may be in a non-optimal state under the influence of multiple factors.Therefore,it is an important idea to consider the combined effect of multiple factors to improve the strength.Under the combined action of silica fume and polypropylene fiber,the strength of foamed concrete increases particularly rapidly.Under the mixing ratio of 9mm fiber length,0.5% volume content and 15% silica fume content,the density grade of 827kg/m3 and the strength of 7.2MPa foamed concrete can be obtained.(2)Orthogonal experiment under different mixture ratio mainly concentrated in the pore size distribution between 300 um to 400 um,polypropylene fiber in the large aperture(> 400 um)bubble walls can be closely connected with bubble wall substrates,does not affect the integrity of the bubble wall,in the small aperture bubbles(< 50 um)around the little polypropylene fiber,it shows that the addition of fiber shape of pores.(3)In the heat transfer simulation,when the same temperature isoline passes through the stomata,the curve always presents a concave shape and then a convex shape.This rule of isoline change is applicable to almost all stomata,and the larger the stomatal diameter is,the more obvious it is.In the pressure simulation,it is found that in the case of no porosity,the stress change is only related to the setting of boundary conditions;when the porosity increases,the stress change is related to both factors.The change of the load only changes the magnitude of the stress,but does not change the trend of the stress change.The stress distribution around the pores is affected by the direction of the load on the one hand,and the surrounding pores on the other hand.