Gypsum Cementing Material Modification Based On Synergistic Optimization

Gypsum and its products have excellent sound insulation,heat insulation,breathing and fireproof performance,known as green building materials.However,short setting time,poor water resistance and crack resistance limit the application.In this paper,?-hemi-hydrate desulfurization gypsum was modified with various solid wastes,based on synergistic optimization,to solve the defects of building gypsum.The desulfurization gypsum block with high strength,water resistance,resistance to cracking was prepared,improving product performance and realizing combined use of a variety of wastes.First of all,waste penicillin mycelium was modified by means of microwave heating and alkali,and the obtained proteins can be utilized as desulfurization gypsum retarder(WPM).Through single factor experiments and successive optimization,the optimum process conditions was determined,namely: microwave reaction time 10 min,temperature 80 ?,pH value 11.Compared with commonly used gypsum retarder(citric acid,sodium citrate,sodium phosphate polymer),WPM retarder not only has excellent retarding effect on desulfurization building gypsum,but also has less strength loss for the gypsum paste because of good synergistic effect in-between.Second,using desulfurization building gypsum as raw materials,and waste industrial solid(steel slag,slag)as mineral admixture,hydration reactions occur under the synergistic effect between the alkaline excitation of carbide slag and high temperature curing,among various materials and the hydration processes,the porosity of desulfurization gypsum was reduced,the compactness was increased,thereby the water resistance and mechanical strength of desulfurization building gypsum were improved.Besides,when steel slag and slag(1:1)composite powder content is 25 %,calcium carbide slag content is 8 %,the flexural strength,compared with the blank,increased from 4.6 MPa to 7.4 MPa,the compressive strength increased from 18.4 MPa to 26.6 MPa,compressive softening coefficient also increased from 0.44 to 0.87.In order to improve anti-cracking performance of gypsum products,AGFP fiber obtained from mechanical crushing was added to composite cementing material system.The effect of different length and dosage of WGFP fiber on the mechanical strength and water resistance of the matrix were studied.The results showed that when WGFP fiber length is 10 to 15 mm,dosage 1.0 %,WGFP fiber has better dispersion effect in the matrix,the flexural strength of gypsum paste increased by 17.3 %,the compressive strength fell by around 0.83 %,the cracking resistance was reinforced.At the same time,the flexural softening coefficient increased to 0.83,water resistance was improved.The results showed there is obvious synergistic effect between AGFP fiber and cement materials.The roughness of WGFP fiber surface after heat treatment,sodium hydroxide solution and EDTA solution treatment increased,and the interface bonding strength enhanced.Comparing the samples treated with EDTA solution with the untreated sample,flexural strength of the former increased by 7.3 %,the compressive strength increased by 10.5 %.At the same time,the softening coefficient increased by 12.5 %.Desulfurization building gypsum was modified by various solid wastes,as waste slag,steel slag,carbide slag and WGFP fiber,solving the problem of short setting time,poor water resistance and crack resistance of the construction gypsum.While improving the desulfurization building gypsum performance,solving the problems of solid waste storage,environmental pollution and waste of resources,realizing the right use of materials,which has high economic and environmental benefits.