Experimental Study On Compressive Performance Of Clay Brick Dust Foamed Concrete Based On Slurry Substitution Method

Compared with ordinary concrete,foamed concrete,as a light-weight porous building material,presents the advantageous performance in heat insulation,sound insulation and noise reduction.The clay brick dust used for foamed concrete comes from the waste building clay bricks,with certain degree of pozzolanite activity.Adding the waste brick scrap into the cement matrix composite material as the admixture can improve the mechanical properties to a certain extent,but will remain a low utilization rate and reduced mechanical properties,if the admixture exceeds certain threshold value.Some scholars have found that replacing cement slurry with clay brick dust can improve the utilization rate while increasing the compressive strength,compared with replacing cement.At present,the number of researches on the preparation of foamed concrete by using clay brick dust instead of cement slurry system is still limited.Based on such gap,this paper studies the effects of the preparation of foamed concrete by slurry replacement method as well as the replacement rate of clay brick dust and the water-cement ratio on the mechanical properties,physical properties,microstructure and pore structure of the foamed concrete under compression.The major conclusions of the research are as follows:replacement rate on the compression properties of clay brick dust foam concrete,it was found that increasing the replacement rate of clay brick dust slurry would also increase the compressive strength of clay brick dust foam concrete.The increase in water-cement ratio had a negative effect on the compressive strength.In this test,the water-cement ratio was 0.4,and the clay brick dust slurry substitution rate was 12%,the maximum compressive strength reached3.21MPa.?2?By studying the influence of water-cement ratio and clay brick dust slurry replacement rate on the physical properties of clay brick dust foam concrete,it was found that with the reduction of water cement ratio and the increase of recycled brick powder slurry replacement rate,the drying density of clay brick dust foam concrete increased correspondingly,the water absorption increased,and the 28-day drying shrinkage and mass loss decreased.Considering the above results and the compounding ratios used in this experiment,the suggested ratio for specimen with better physical properties are:the water-cement ratio of 0.4,the replacement rate of the clay brick dust slurry of 12%,the drying density of 670kg/m³,and the water absorption rate of 41.79%.?3?By studying the influence of water-cement ratio and clay brick dust slurry replacement rate on the hydration products and micro-morphology of clay brick dust foam concrete,it was found that with the water-cement ratio set smaller,the recycled brick powder replacement rate was greater,the clay brick dust performed more effectively in its pozzolanic activity,so that more hydration products was generated by the reaction,and more Ca?OH?₂produced by cement hydration was consumed,thereby accelerating the cement hydration reaction.On the other hand,due to the micro-aggregate effect produced by the incorporation of clay brick dust,it can fill tiny pores to make the microstructure denser.?4?By studying the influence of water-cement ratio and clay brick dust slurry replacement rate on the pore structure of clay brick dust foam concrete,it was found that based on the slurry replacement method,clay brick dust can improve the pore structure and decrease the through holes.Specifically,as the slurry substitution rate increased,the pore size distribution became more even and the porosity decreased.For water-cement ratio,the increase of water-cement ratio led to discontinuous pore size distribution and increased porosity.