Study On Mechanics And Thermal Properties Of Exterior Wall Insulation Materials For Green Energy-saving Buildings

With the rapid development of China's economy,the construction industry is also developing.With the continuous research on new materials and new technologies,a variety of new building materials are also emerging,among which the foam concrete thermal insulation material has the advantages of thermal insulation,sound insulation,good fire protecting performance,etc.,and is widely used in the construction industry.In this paper,PC42.5R,mineral powder,silica fume,animal protein foaming agent and other main raw materials were used to prepare foam concrete with dry density of about 400kg/m~3 by using high-speed stirring foaming.The thermal and mechanical properties of the foamed concrete were tested by single factor test and orthogonal test.Finally,the foamed concrete with low thermal conductivity and suitable strength was prepared.Firstly,the foaming agent and cementing material were modified.Four substances were selected as foam stabilizing agents in the experiment to study the effect of foam stabilizing agents on the properties of foaming agent,such as foaming times.Finally,K12 was selected as foam stabilizing agent.The effects of mineral powder and silica fume on the mechanical properties of cementitious materials were studied.Then,by studying the single-factor variable test of low-density foamed concrete,the mechanical and thermal properties of foamed concrete were studied,focusing on the influence of water-binder ratio,foam dosage,water reducer dosage and polypropylene fiber on mechanical properties and thermal properties,and the following conclusions were drawn:(1)within a certain range,the compressive strength of foamed concrete first increases with the increase of water-cement ratio,then decreases,and the thermal conductivity gradually increases with the increase of water-cement ratio;(2)with the increase of foam content,the compressive strength of foamed concrete gradually decreases,and the thermal conductivity first decreases and then increases;(3)the compressive strength of foamed concrete increases with the increase of the dosage of water reducer,and the thermal conductivity is related to the pore structure;(4)polypropylene fiber can improve the pore structure of porous concrete,improve thermal insulation performance,and has little impact on compressive strength.Finally,through orthogonal experiment,the order of the influence of various factors on the dry density of foamed concrete was studied:foam dosage>water-reducing agent content>water-binder ratio>fiber content.The order of influence of various factors on the compressive strength of low-density foam concrete at 14d is as follows:water-reducing agent content>water-binder ratio>foam dosage>fiber content.The order of influence of various factors on the thermal conductivity of foam concrete is as follows:water-reducing agent content>water-binder ratio=foam dosage>fiber content.Finally,the foam concrete with compressive strength of 1.12MPa,dry density of 395kg/m~3 and thermal conductivity of0.161M/(m·k)was prepared.