Study On The Preparation Of Gypsum Plaster For Base Coating By Flue Gas Desulphurization Gypsum

The content of calcium sulfate dehydratein desulphurized gypsum is higher than that of natural gypsum.It can.be used as a cementing material to produce gypsum plaster after calcination.It has the advantages of light quality,fire protection,thermal insulation,environmental protection,quick construction and good adhesion to the base compare withCement plaster mortar.It has obvious social and economic benefits.Through exploring the effectofcalcination system on the performance of the desulfurization building gypsum,determine the appropriate calcination temperature and calcination time.By studying theeffectofspecies and dosage of the retarder and water-retaining agent on desulfurization building gypsum underappropriate calcination system,choose the suitable type and dosage of the retarder and water-retaining agent.Then determine the glue sand ratio,modifygypsum plaster by inorganic gelled material,determine the gypsum plaster recipe.The results showed that when the temperature is 150 ?,2h longtime,the performance of the desulfurization building gypsum is best,waterrequirementofnormalconsistency is 0.67,the initial setting time and the finial setting time is 9min and 15min,2h flexurall strength is 3.86MPa,compressive strength is 9.45MPa.Retarder PE and water-retaining agent HEMC200000 ha-ve a goodadaptation to the desulfurization building gypsum.When the PE content is 0.1%in the building gypsum,the comprehensive performance of the building gypsum is best,the initial setting time and the finial setting time is 87min and 98min,flexurall strength is 6.15MPa,compressive strength is 17.5MPa.When the water-retaining agent content is 0.2%of the building gypsum,water-retention rate is 97.9%,flexurall strength is 6.0MPa,compressive strength is 17.2MPa,flexurall strength is 6.6MPa,tensile adhesive strength is 0.79.It is also suitable for the change of moisture content in the substrate.When the glue sand ratio is 1:1.0,the amount of mineral powder and cement content is 25%and 5%respectively,gypsum plaster has the best comprehensive performance,the flexurall strength and compressive strength were 4.7MPa and 16.7MPa respectively,the water absorption rate is 17.2%and the softening coefficient is 0.68.The performance of plastering gypsum with fly ash is little changed.At last,the final recipe of the gypsum plaster for base coatingwas determined.The dosage of retarder PE and water retention agent HEMC200000 are 0.09%and 0.2%of gelled materialrespectively,glue sand ratio is 1:1.0.Products performances were tested,the results meet the "GB/T28627-2012" of the gypsum plaster.The formula for gelled material of gypsum plaster for base coating is 70%of gypsum,25%of mineral powder and 5%of cement,and the dosage of retarder PE and water retention agent HEMC200000 are 0.09%and 0.2%of gelled materialrespectively.The softening coefficient is 0.68,70%higher than the benchmark.