Research And Application Of Modification Of Lightweight Foam Concrete Foaming Agent

This paper aims to develop a high performance concrete foaming agent that can be used in lightweight foam concrete.The whole work can be divided into two parts.The first part is the experimental study of concrete foaming agent,and the second part is the application of concrete foaming agent to the cement slurry and the preparation of lightweight foam concrete with a density of about 300 kg/m~3.And then determine the performance parameters of the foam concrete sample.The research of concrete foaming agent is mainly to determine the foaming agent by comparing the foaming properties of various foaming agents,and then to improve the foaming agent by combining single and multiple stabilizing foaming materials.The foaming property of foaming agent is evaluated mainly by foaming volume and foam half life.The preparation of foam concrete is to find the optimal parameter ratio by exploring parameters such as water-cement ratio,foam content and early strength agent,and to determine the compressive performance of foam concrete.(1)Determine the foaming agent.Tested by sodium dodecyl sulfate,sodium alpha-olefin sulfonate,sodium dodecyl benzene sulfonate,sodium lauryl ether,sodium alcohol ether sulphate.The foaming test of different blowing agents was carried out by selecting the stirring speed of the electric mixer at 1400 r/min.The results show that the foaming properties of sodium dodecyl sulfate and sodium alpha-olefin sulfonate are similar.Sodium dodecyl sulfate is chosen as the foaming material considering the cost and other reasons.(2)Determine the best experimental conditions for foaming agent.Through the foaming experiment on sodium lauryl sulfate,the optimum conditions for foaming were as follows:stirring speed 3000 r/min,sodium dodecyl sulfate optimal blending amount 0.6 wt%,at this time,the foaming volume of the foaming agent was 970 ml,and the foam half-life was 580 s.(3)Selection of Thickener.The thickeners of concrete foaming agents can be divided into two categories according to their action principles.One is to change the molecular arrangement in the foam liquid film,mainly lauryl alcohol,modified polyethoxylated silicone,sodium chloride,ect,and the other is to increase the viscosity of the foaming agent,polyacrylamide,hydroxypropyl methyl cellulose,sodium polyacrylate,carboxymethyl cellulose sodium,hydroxyethyl cellulose and so on.The first kind of thickening agent lauryl alcohol and modified polyethoxylated silicone has the best foam stability.The best mixing amount is 0.05 wt%and 0.25 wt%respectively,the foaming volume is 885 ml and 870 ml,and the foam half-life is 2145s and 1850 s respectively.Sodium polyacrylate and carboxymethyl cellulose sodium in second kinds of thickeners had better effect,the best mixing amount is 0.25 wt%and 0.13 wt%,the foaming volume is 720 ml and 750 mL respectively,and the half-life of the foam is 2700 s and 1750 s respectively.Finally,the two kinds of thickeners are mixed,and finally the composition and content of the foaming agent is determined to be 0.6 wt%sodium dodecyl sulfate+0.05 wt%lauryl alcohol+0.20 wt%Sodium polyacrylate,the foaming volume is 670 ml and the foam half life is 12070 s.(4)Preparation of lightweight foam concrete.The slag Portland cement was selected,and calcium chloride is used as an early strength agent.Finally,it was determined that the performance of the foam cement is the best when the water cement ratio is 0.5?the dosage of early strength agent is 13 wt%(cement quality)and the foam volume is 1.15L per 250g cement,and the compressive strength is 0.45MPa and the heat insulation coefficient is 0.073 w/m·k.