Preparation And Properties Of Alkali-activated Foamed Concrete

Foamed concrete has the characteristics of fire prevention and durability,as a building insulation material has a broad space for development.At present,the application of cement-based foam concrete is more extensive,but cement is a kind of high energy consumption,high pollution material,so the use of environmentally-friendly cementitious material to replace cement to prepare foam concrete is inevitable.Alkali slag cement is a kind of environmental protection cementing material with low cost,low energy consumption and low emission.This project uses alkali-activated slag cement to prepare alkali-activated slag(AAS)foamed concrete,in order to obtain green foamed concrete.This topic research the concentration of foaming agent and stabilizing agent concentration of alpha olefin sulfonate(AOS),sodium dodecyl sulfate(K12)and sodium alcohol ether sulfate(AES),the influence of three kinds of foaming agent of foaming performance,and the influence of three kinds of foaming agent of AAS foam concrete,optimizing the best foaming agent,by optimizing the preparation of AAS foam concrete foaming agent,dosage of activator and bubble influence on its performance,and to establish AAS foam concrete performance prediction model.The following conclusions are drawn:(1).The optimal ratio of AOS foaming agent was 0.4%and 0.08%respectively,and the optimal ratio of K12 foaming agent was 0.6%and 0.12%,respectively.The optimal concentration of AES foaming agent is 0.08%,and the concentration of foam stabilizer is0.08%.The performance of the three foams is similar,and the foam stability of AOS and K12 is slightly better than AES.The foam expansion ratio of the three foams is 21-25,the bleeding water is 62-68mL,and the settling distance is 1-2 mm.(2).The effective foam ratio can be used to characterize the stability of foam in slurry.The effective foam ratio and porosity have great influence on the dry density of AAS foamed concrete.With the increase of foam content,the effective foam ratio of AES decreased significantly,while that of K12 and AOS decreased slightly.AES can reduce dry density at low foam content.AOS foamed concrete has the highest compressive strength.When porosity is similar,the average pore size and pore size distribution have great influence on the thermal conductivity and mechanical properties of AAS foamed concrete.The average pore diameter of AOS foamed concrete is less than that of K12foamed concrete and AES foamed concrete.AOS foamed concrete has a narrow pore size distribution,most of which are less than 400 m in diameter.The average roundness value of the three pore is basically the same.Foam stability is the main factor affecting the pore structure of AAS foamed concrete.AOS is preferred for the preparation of AAS foamed concrete.(3).When AAS foamed concrete is prepared by AOS,the activator content should not exceed 6%.When the activator content is 4-6%,the foam content increases with the constant activator content,the dry density and compressive strength of AAS foamed concrete decrease,the water absorption increases,and the number of large and connected pores increases.When the foam content is unchanged,the dry density increases with the increase of activator content,the water absorption decreases,the number of large pores increases,but the number of connected pores decreases.The influence of base activator and foam content on average pore size and pore shape is small.(4).When the activator content is 5%,AAS foamed concrete has the best performance.When the foam content is in the range of 3-12%,the dry density of AAS foamed concrete is 610-1100 kg/m~3,the compressive strength is 1.62-13.27MPa,and the thermal conductivity is 0.1025-0.1720 W/(m·K).Steam curing can effectively improve the compressive strength of AAS foamed concrete.When the dry density is 655 kg/m~3,steam curing at 80?increases the compressive strength from 2.04MPa to 3.47MPa.(5).When the compressive strength increases with activator of 4%or 6%,the dry density,compressive strength and foam content of AAS foamed concrete all conform to Boltzmann function.When the activator content is 5%,the dry density is in line with the foam content,and the compressive strength is in line with the Boltzmann function.When the activator is 4-6%,the water absorption and foam content conform to the power function y=ax~b.The performance model can be used in the mix design of AAS foamed concrete.