Preparation And Properties Of Lightweight Gypsum Plaster

Lightweight gypsum plaster is a green plastering material on the market,and its appearance has changed the traditional way of plastering cement-based materials.Gypsum plaster can not only avoid the problems of dry shrinkage,poor adhesion,expansion cracking and hollowing drum caused by traditional plastering,but also the lightweight gypsum plaster has smaller volume density and lower thermal conductivity,which can reduce the matrix itself and makes the building's energy consumption lower.From the perspective of constructability and economy,gypsum has a wide range of sources and a short construction period,which reduces both the cost of engineering materials and labor,and also accelerates the construction schedule.Under the policy of energy-saving and emission reduction in China,lightweight gypsum plaster replaces traditional cement plastering,which will become a development trend.It has theoretical significance and practical value for the preparation and performance of lightweight gypsum plaster.In this experiment,by studying the effects of different retarders on the setting time and hardening strength of phosphogypsum,a retarder with good adaptability to phosphogypsum was determined.The effects of different types of cellulose ether on the standard consistency water requirement,setting time,water retention rate and mechanical properties of phosphogypsum were studied to determine the optimum cellulose ether type for the preparation of lightweight gypsum plaster.By using large water-cement ratio to conversion to light fraction,and then the related changes in density and its rheological properties are explored.After mastering the basic laws,the slag and clinker were used to modify the phosphogypsum to prepare modified lightweight gypsum plaster.Then has researched the mechanical properties,rheological properties,volume stability,density change,water retention and water resistance,and microscopic mechanism of lightweight gypsum plaster.The results of the study showed that thecombination property of gypsum was better when citric acid and 100,000 Pa·s of HPMC were used as retarders and water retaining agents.Through the large water-cement ratio,the dry density of the hardened paste can be below 1000 Kg/m~3,and take the rheological property and mechanical properties in to consider,the water-cement ratio is about 0.9.By modification,the strength loss due to the large water ratio can be compensated to some extent,and there is no significant volume change.The addition of retarder and water retaining agent will affect the comprehensive performance of the modified lightweight gypsum plaster.But when the dosage is controlled within a certain range,the overall impact will be small.Through the microscopic analysis of the modified lightweight gypsum plaster,the ettringite and hydration products formed by the reaction of the slag and the clinker are found,so that the overall performance of the hardened body is improved.