Study on Composition Optimization and Water Resistance Improvement of Phosphogypsum Artificial Aggregate
In view of the problems that phosphogypsum occupies a large amount of cultivated land resources and is easy to produce environmen-tal pollution,the artificial aggregate was prepared by phosphogypsum,slag,fly ash,cement and other materials to promote the resource utilization of phosphogypsum.Through orthogonal design,the optimal ratio was 9％ slag powder,10％ fly ash,5.5％ cement,75.5％ phosphogypsum,and artificial aggregate was prepared by pressing the raw materials.The maximum 28 d cylinder compressive strength of aggregate could reach 7.2 MPa,and the water absorption rate at 1 hour was less than 10％.By analyzing its curing mechanism,it could be found that the materials of gelling system react with each other,and the materials stimulated the hydration reaction of phosphogypsum to produce hydration products including ettringite and calcium silicate hydrate gel.The hydration products gradually filled the gaps between particles,and the bonding between particles became closer,making the strength of phosphogypsum based aggregate sustainable.The water resistance was improved by direct mixing,pretreatment of phosphogypsum and immersion coating.It was found that the water-repellent agent OS could improve the interface hydrophilicity of the aggregate in different treatment methods,and the contact angle reached 122.7° after coating treatment,the aggregate surface became hydrophobic.Coating treatment had little influence on the strength of aggregate,and could effectively improve the water resistance of aggregate.
万方数据
维普
