关键词: 改性磷石膏, 抹灰砂浆, 有机硅防水剂, 耐水性能

Abstract: In order to solve the problem of poor water resistance of phosphogypsum plaster mortar and promote the application of phosphogypsum plaster mortar in construction industry,modified phosphogypsum was obtained by pretreating,and the effects of waterbinder ratio and water reducing agent dosage on the physical properties,mechanical properties and water resistance of modified phosphogypsum plastering mortar were studied.The water resistance of phosphogypsum plastering mortar was further improved by introducing silicone water repellents into the system.The results show that the mixing amount of water reducing agent and waterbinder ratio are the main factors affecting the properties of phosphogysum plastering mortar.Low waterbinder ratio and low water reducing agent dosoge are beneficial to the improvement of mechanical properties and water resistance,and the mixing amount of water reducing agent should not be higher than 0.9%.Although silicone water repellents can effectively improve the water resistance of phosphogypsum plaster mortar,it will adversely affect its strength,and its dosage should not be higher than 0.6% in practical application.The gel and ettringite in the hydration product can fill the gap between the crystals of calcium sulfate dihydrate,which is beneficial to the increase of the density,strength and softening coefficient of the specimen.And the silicone water repellents will form a waterproof film on the surface and the gap of the hydration product,which can further improve the water resistance of the specimen.

Key words: modified phosphogypsum, plaster mortar, silicone water repellents, water resistance