工业副产煅烧石膏耐水性能的改性研究

Modification of Water Resistance of Calcined Industrial By-Product Gypsum

工业副产煅烧石膏可广泛用于建筑砌块和板材等制品的生产,耐水性能对其在潮湿环境中使用具有重要的影响。优选可再分散乳胶粉、有机硅粉末为防水外加剂,通过单掺和复掺的方式研究其对工业副产煅烧石膏及工业副产煅烧石膏-生石灰两种胶凝材料体系强度及耐水性的影响,采用SEM观测其微观形貌,探讨其强度及耐水性影响机理。研究结果表明:外加剂的掺入会破坏二水石膏晶体的结构骨架,对胶凝材料体系的抗压强度有负面影响,对煅烧石膏-生石灰体系的抗折、耐水性改善效果较好,在该体系中复掺2.5%可再分散乳胶粉和0.9%有机硅粉末,试样2 h吸水率为3.4%,2 h抗折、抗压软化系数分别为0.67、0.72,2 h抗折、抗压强度分别为2.77 MPa、5.40 MPa,绝干抗折、抗压强度分别为5.78 MPa、12.85 MPa,可再分散乳胶粉在二水石膏晶体表面会形成一层膜,而有机硅粉末对二水石膏晶体无影响。

The calcined industrial by-product gypsum can be widely used in the production of building blocks and plates,and its waterproof property has an important role on the application in wet environments.This paper chooses the redispersible latex powder and silicon powder as waterproof admixture,and studies its effect of strength and water resistance on the calcined industrial by-product gypsum and calcined industrial by-product gypsum-quicklime by the ways of single mixing and complexes mixing. At the same time,the mechanism of its strength and water resistance is discussed by using SEM to observe its microstructure. The results show that,the addition of admixture will destroy the structure framework of dihydrate gypsum crystals,and have a negative influence on the compressive strength of the cementitious material system,and the effect on the fracture resistance and water resistance of the calcined gypsum-quicklime is better. When mixed 2. 5%redispersible emulsion powder and 0. 9%organic silicon powder in calcined industrial by-product gypsum-quicklime cementitious material,the properties of the samples are as follows： the water absorption rate of 2 h is3. 4%,the flexural and compressive softening coefficients of 2 h are 0. 67 and 0. 72,the flexural strength and compressive strength of 2 h are 2. 77 MPa and 5. 40 MPa,the breaking resistance and compressive strength are5. 78 MPa and 12. 85 MPa. A layer of film can be formed on the surface of the dihydrate gypsum crystals by mixing the redispersible latex powder,and the organic silicon powder has no influence on dihydrate crystals.