Preparation And Performance Optimization Of Foam Concrete Containing Cross-linked System

Foam concrete has been widely used as a kind of thermal insulation material in building external wall thermal insulation engineering.The test of comprehensively considering the foam stability and thermal insulation performance,the physical foaming and cross-linking system were combined to prepare high-quality 500 grade foam concrete.Firstly,foam concrete with better performance was prepared by adjusting the water-cement ratio and the content of foam stabilizer;Secondly,the cross-linked system was introduced into foam concrete by adding polymeric monomer and initiator to optimize its pore structure,so as to successfully prepare high-quality foam concrete with stable foam performance and excellent thermal insulation performance.Finally,in order to further study the internal heat transfer behavior of foam concrete containing cross-linked system,the two-dimensional model of foam concrete was reconstructed to simulate and verify the steady and transient heat conduction processes.The main research contents and results are as follows:(1)Through exploring the influence of water-cement ratio on the performance of foam concrete,it was found that when the water cement ratio increased from 0.35 to 0.50,the consistency of cement paste became smaller,the slurry and foam were fully integrated,which could better wrap bubbles.However,if the water-cement ratio was too small or too large,the mixture would be too thick and hard to vibrate and compact or produce segregation and delamination,which would seriously affect its later strength and thermal insulation performance.On this basis,the optimal water-cement ratio was determined to be 0.35.(2)Through exploring the influence of the content of foam stabilizer on the performance of foam concrete,it was found that the appropriate amount of foam stabilizer had the effect of optimizing the pores,which was conducive to increasing the number of circular and closed pores inside the foam concrete.At the same time,it could reduce the heat conduction efficiency of foam concrete and improve the thermal insulation performance of foam concrete.On this basis,the optimal content of foam stabilizer was determined to be 30%.(3)Through exploring the influence of the content of polymeric monomer on the performance of foam concrete containing cross-linked system,it was found that PAMPS polymer was constantly generated with the increase of the content of polymeric monomer,and their unique three-dimensional network skeleton filled the pores between the slurry to refine the pore size.The membranes of PAMPS polymer quickly wrapped the air bubbles with the gradual intensification of the cross-linking reaction,which would cause a sharp increase in the number of pores inside the foam concrete and the porosity increased as well.On this basis,the optimal content of polymeric monomer was determined to be 1.5%.(4)Two-dimensional model was established based on the pore structure data of foam concrete containing cross-linked system,and the numerical simulation of steady-state and transient-heat transfer was carried out.The results showed that the heat conduction path was more tortuous when there were more large pores,and the heat conduction path changed more gently when there were more small pores.When the small pore ratio reached 25% or more,the thermal insulation performance of foam concrete was significantly improved.The heat from the high temperature surface of the test block gradually transferred to the low temperature surface over time.The heat flow direction was more likely to be transmitted through large holes and the thermal insulation effect was better when the small holes were more distributed.