Preparation Of Biological Foaming Agent And Its Application In Foam Concrete

With the implementation of energy saving and emission reduction policy,foam concrete has become the best choice to replace organic insulation materials at present,and has been rapidly developed in the building materials industry.At the same time,as an important raw material for the production of foam concrete,foaming agent has also been widely studied.However,the foaming agent used in the production of foam concrete has the disadvantages of single performance,difficult to control the distribution of bubbles in cement paste,shortage of some raw materials and pollution of environment,resulting in poor performance and high cost of formed foam concrete.Furthermore,it is difficult to prepare foam concrete with density grade lower than A05using ordinary Portland cement and existing foaming agent.Therefore,in this paper,a kind of microbial foaming agent was prepared from natural yeast,and the mechanism and properties of foaming agent were studied.Then it was mixed with surfactant obtain bio-based foaming agent and study the effect of surfactant type and dosage on foam properties of bio-based foaming agent.On the basis of the above,the bio-based foam concrete of A03-A08 density grade was prepared by self-made bio-based foam agent to study the physical and mechanical properties and microporous structure of bio-based foam concrete of different density grade.The results are as follows:?1?The microbial foaming agent cannot only produce CO₂ to form foam by yeast fermentation,but also decompose the nutrients in the medium by using the yeast's own biochemical reaction to reduce the surface tension of the foaming agent solution and the air bubble is introduced under external force.When the microbial foaming agent was mixed with 0.5%CTMAB,the foam performance of the bio-based foaming agent was the best,the foaming multiple was 17,1 h settlement distance was 2 mm,and the1 h bleeding rate was 48.3%.?2?The dry density of A06-A08 density grde bio-based foam concrete was 620kg/m³?730 kg/m³?800 kg/m³;the compressive strength was 2.5 MPa?3.5 MPa?5.5MPa;the thermal conductivity was 0.12 W/?m·K??0.15 W/?m·K??0.17 W/?m·K?;the water absorption was 48%?46%?43%;porosity was 79%?75%?73%;pore size was1080?m?740?m?560?m;average pore size was 601?m?501?m?384?m;pore shape factor was 0.939?0.970 and 1.004.?3?The dry density of A03-A05 density grde bio-based foam concrete was 310kg/m³?430 kg/m³?510 kg/m³;the compressive strength was 0.9 MPa?2.0 MPa?3.1MPa;the thermal conductivity was 0.07 W/?m·K??0.08 W/?m·K??0.10 W/?m·K?;the water absorption was 112%?95%?89%;porosity was 90%?88%?85%;pore size was 760?m?680?m?460?m;average pore size was 515?m?431?m?373?m;pore shape factor was 1.095?1.043 and 0.985.