Preparation of High Strength Gypsum Product with Wet-Base α-Hemihydrous Gypsum
In order to produce high strength gypsum products from wet-base α-hemihydrous gypsum,the ideal preparation method was identified by analyzing the effects of aging time,grinding time,molding temperature and retarder content on setting time and strength of high strength gypsum.Additionally,scanning electron microscopy and X-ray diffraction were used to clarify how each aspect affected strength.The results show that longer aging period results in lower strength and shorter setting duration of gypsum.As the grinding time prolongs,the setting time of gypsum significantly shortens,and the strength of product increases first and then decreases.The higher the slurry temperature is,the longer the gypsum setting time is,and the lower the product strength is.The optimal preparation process is aging time of 5 min,grinding time of 20 s,and slurry temperature of 20 ℃.On this basis,adding 0.08％(mass fraction)retarder can effectively prolong the setting time of gypsum and improve the hardening strength.The prepared gypsum products have excellent performance,with a drying flexural strength of 14.1 MPa and a drying compressive strength of 58.3 MPa.The microscopic test results indicate that various process parameters can affect the compactness of the internal structure of gypsum and the growth and development of dihydrate gypsum crystals by changing the water content and hydration process of gypsum,ultimately affecting the hardening strength of product.
wet-base α-hemihydrous gypsumhigh strength gypsum productpreparation processmechanical propertysetting timewater requirement of normal consistencydynamic hydrothermal method
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