Study on the properties of high temperature modified phosphogypsum with calcium oxide on cement based cementitious ma-terials
Phosphogypsum is a solid waste generated in the phosphorus chemical industry,mainly composed of CaSO4·2H2O.It has the characteristics of high yield and complex composition,which hinders its application in cementitious materials.This study utilizes the alkalinity of calcium oxide to remove acidic impurities from phosphogypsum,explores the mechanism of calcium oxide modified phosphogypsum,investigates the physical properties of phosphogypsum cementitious materials,and analyzes the hydration products of the cementitious materials using SEM.The results show that calcium oxide can eliminate acidic impurities in phosphogypsum and weaken its inhibitory effect on the directional growth of dihydrate gypsum crystals;After adding calcium oxide,the stability of the ce-mentitious material is qualified,and the initial and final setting times both decrease;The addition of calcium oxide is beneficial for the development of the strength of cementitious materials,and the optimal amount of calcium oxide is 2％;The SEM results show that calci-um oxide eliminates the inhibitory effect of impurities,enhances hydration,and forms layered dihydrate gypsum crystals,which is bene-ficial for the development of the strength of cementitious materials.
calcium oxidephosphogypsumhigh temperature modificationcement mortar
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