Study On Ultra-light Polymer Modified Foamed Cement

According to current standards and literature reports,the dry apparent density of foamed cement is generally greater than 200kg/m³,the thermal conductivity is generally greater than 0.06W·m^-1K^-1,and the water absorption rate is generally not more than 10%,although it has excellent fireproof performance.However,compared with organic insulation materials,their thermal and mechanical properties need to be further improved to meet the needs of building energy conservation.This article intends to study the main performance indicators of foamed cement,expect to get a dry apparent density of less than 160kg/m³,thermal conductivity of less than 0.05W·m^-1K^-1,compressive strength greater than 0.3MPa and water absorption less than 3.0%of the super light foaming cement.Based on the existing research of the research group,this paper first determined the basic blending ratio of ultra-light foamed cement by changing the blending amount of foaming agent,early strength agent and fiber:the amount of foaming agent is 7.5⁸.5wt%;the amount of early strength agent A-3 is 5.3%and the fiber content is0.25%.The main properties of the ultra-light foamed cement prepared under this condition are:dry apparent density of 148.6 kg/m³,28d compressive strength of 0.25MPa,thermal conductivity of 0.043 W·m^-1K^-1,and water absorption of 19.6%.Secondly,the ultra-light foamed cement was blended with a polymer emulsion to determine the basic mix ratio of ultra-light polymer modified foamed cement.And through the fine adjustment of water-binder ratio,foam stabilizer,and incorporation of carbon nanotubes?CNTs?and carbon black,etc.,ultra-light polymer modified foamed cement performance improvement tests were conducted.It is concluded that the performance of the ultra-light polymer modified foamed cement between 0.516and 0.556 can meet the requirements of the research objectives.FA-CNTs has the best compressive strength enhancement effect.The compressive strength was 0.42 MPa when 0.42 wt%of the binder was added.The porosity,pore size distribution,and hydration products were analyzed using MIP,X-CT,and TG-DSC methods.After incorporation of FA-CNTs,compared with un-doped reference samples,the dry apparent density is basically the same,the porosity of the micro-structure of the bubble wall is decreased,the average pore size is smaller,and the porosity ratio is less than 200 nm and the ratio is higher.The degree of cement hydration is higher.Thirdly,on the basis of the basic ratio of ultra-light polymer modified foamed cement,the method of mixing the water-repellent agent,the surface coating penetrating crystalline water repellent agent,and the internal and external spray coating compounding method is adopted.The effect of the ultra-light polymer modified foamed cement on the water absorption rate was studied,and the waterproof mechanism was analyzed.It is concluded that the volumetric water absorption of the ultra-light polymer-modified foamed cement can be reduced to 3.69%under the conditions of sprayed penetrating crystalline water repellent on the exterior.Finally,the solid waste content was increased to 50%by weight of the cementitious material,and the activity of fly ash and furnace bottom slag was 94.5%and 68.7%,respectively.The influence of solid waste content on the performance of ultra-light polymer modified foamed cement was studied.Through the above research on the properties of foamed cement,the optimum mixing ratio and suitable preparation process of ultra-light polymer modified foamed cement were obtained.