Study On Preparation And Properties Of Slag Foam Concrete Wall

Wall insulation is the foundation of building energy efficiency.Compared with organic thermal insulation materials,inorganic thermal insulation materials,especially,ordinary Portland cement(OPC)based foam concrete have the advantages of low prize,fireproof,durable,non-toxic,harmless and so on.However,the application of OPC based foam concrete is limited in part due to its characteristic disadvantages long setting time,low mechanical strength and high water absorption rate.As a new type of cementing material,slag foam concrete which is fabricated by mixing OPC with slag has the advantages of high strength,utilization of waste and reduction of cement clinker dosage.This topic proposes the technical idea of using large amount of slag instead of cement to prepare foam concrete,in order to obtain inorganic insulation materials with light weight,high strength and good waterproof performance.In this paper,the cement coagulation test and foaming agent test,mechanical properties of slag foamed concrete and functional modification of slag foamed concrete were carried out.The influence curves of parameters on the properties of products were obtained,and the reasons for strength changes of products were analyzed by scanning electron microscopy(SEM)on representative samples.The results show:(1)When 0.16%HPMC was added to 20 times diluted animal protein foaming agent solution,the foam settlement distance and bleeding water amount were the minimum,and the foam stability was the best.From the effect of reducing cement setting time,calcium chloride has the best effect,followed by ferric chloride,and calcium sulfate and sodium sulfate have the same effect.(2)With the increase of slag content,the compressive strength of the product increases first and then decreases.When the slag content is 40%,the compressive strength of the 7d and 28d of the product reaches a maximum.As the water-to-binder ratio increases,the compressive strength of the slag foam concrete increases first and then decreases.When the water-to-binder ratio is 0.6,the maximum compressive strength could be obtained.(3)The early strength agents of calcium chloride and ferric chloride improved the compressive strength of slag foam concrete 7d and 28d.At the same dosage,calcium chloride contributes more to the improvement of the strength of the product.The influence of the ratio of sand to glue and the content of ceramsite on the strength of slag foamed concrete is as follows:with the increase of fine sand content,the mechanical strength of the product is gradually reduced;the incorporation of ceramsite has a certain improvement on the compressive strength of slag foam concrete,the best blending.The amount is around 4%.(4)Three kinds of waterproofing agents have certain effects on the waterproof performance improvement of slag foam concrete.When the coating parameters of silicone oil,paraffin emulsion and sodium methylsilicate waterproof agent were 696g/m2,the water absorption rate of the products were 3.4%,30.79%and 32.6%,respectively.Therefore,for improving the waterproof property of products,silicone oil has the best effect,paraffin emulsion has the second best effect,and sodium methylsilicate has the worst effect.(5)Both vitrified microspheres and expanded perlite can improve the thermal insulation properties of slag foam concrete effectively.When the content of vitrified microspheres and expanded perlite is 7%,the thermal conductivity of the products are 0.096W/(m K)and 0.082 W/(m·K)respectively.Compared with the reference group,the thermal conductivity are decreased 25%and 36%respectively.As the amount of insulation material increases,the strength of the product increases first and then decreases.The optimum amount of vitrified beads is 5%,and the optimum amount of expanded perlite is 3%.