Preparation And Performance Test Of Foam Desulfurization Gypsum Materia

Desulfurized gypsum is a by-product of gypsum produced by wet flue gas desulfurization after the power generation reaction of industrial power plants.Because it has not been effectively utilized,it is in a state of accumulation in large quantities,causing harm to the environment and ecology,and also a huge waste of resources.Desulfurized building gypsum has good cementitious properties.If the desulfurized building gypsum is used instead of cement to prepare foamed concrete materials,a new building material with light weight,high strength and thermal insulation can be obtained while improving the utilization rate of desulfurized building gypsum.For this reason,this subject takes the desulfurized building gypsum as the matrix material,and studies the foamed desulfurized gypsum material by adding foam,fiber and admixture in it.The main research contents and results are as follows.（1）By measuring the expansion degree and setting time of desulfurized plaster of Paris,the effect of water reducing agent and retarder on the performance of desulfurized plaster of Paris was explored.The results show that the fluidity of gypsum is better when the water-reducing agent content is 0.5%,and the ratio of appropriate water-reducing agent to water-paste can increase the strength of desulfurized building gypsum,but at the same time,it will cause the setting time to be too short,so that the gypsum slurry cannot be cast and formed..Adding a retarder can solve the problem of too short setting time,and the retarder with a dosage of 0.1%can effectively improve the fluidity of desulfurized gypsum of construction.（2）The variable control method was used to investigate the effects of different foam contents on the properties of the desulfurized gypsum material,and combined with microscopic analysis and regression analysis to explore the mechanism of foam in the desulfurized gypsum material.The results show that the increase of the foam content will cause the volume expansion of the gypsum slurry.With the increase of the foam content in the range of 4%to 12%,the matrix strength,softening coefficient,dry density and thermal conductivity of the foam desulfurized gypsum all decrease.The water absorption and porosity gradually increased.Through microscopic analysis,it is found that the greater the foam content,the worse the internal structure stability.Combined with regression analysis,it is found that the correlation between porosity and water absorption is the best,and the goodness of fit R² is 0.9707.（3）Single factor experiment was used to explore the influence of fiber type and dosage on the properties of foamed desulfurized gypsum matrix,and to explore the mechanism of fiber in foamed desulfurized gypsum.The results show that,in the range of 0.6%～1.4%,the basalt fiber and glass fiber alone can keep the original dry density and porosity of the foamed desulfurized gypsum matrix,and at the same time improve the compressive strength,flexural strength and water resistance.Meet the requirements of light weight and high strength.When two kinds of fibers are mixed and the total content is determined,when the proportion of glass fibers is larger,the mechanical properties of foamed desulfurization gypsum are greatly improved.After microscopic analysis,it is found that the formation of skeleton in the gypsum matrix is the main reason for the increase in strength.（4）Single factor test and orthogonal test were used to study the modification of foamed desulfurized gypsum-based composite materials.Combined with XRD and SEM and other test methods,the effects of composite Portland cement,slag powder,and microsilica on foamed desulfurized gypsum materials were investigated respectively.the modification effect,so as to obtain the optimal proportioning scheme.The results show that the admixture reacts with gypsum to generate orgonite（AFt）and C-S-H gel and other substances,which can fill the gaps of gypsum crystals,which can effectively improve the strength and water resistance of the foamed desulfurized gypsum matrix.The order of performance impact from large to small is:micro silica fume>composite Portland cement>slag powder.Through the orthogonal test,it is concluded that the optimal proportioning scheme of foamed desulfurization gypsum-based composite materials is A₂B₁C₂,that is,the amount of composite Portland cement.12%,10%of slag powder,10%of microsilica.