外加剂对磷建筑石膏的改性及其机理研究

制备磷建筑石膏制品是磷石膏资源化利用的一条重要途径，而合适的改性技术是保证建筑石膏制品能够工业化生产的关键。分别利用3种减水剂、3种缓凝剂、2种黏结剂、2种保水剂对磷建筑石膏进行改性，探讨外加剂品种对磷建筑石膏的适应性，研究外加剂掺量对磷建筑石膏的性能影响规律，并采用扫描电镜对优选出的外加剂的改性机理进行分析。结果表明：聚羧酸减水剂(PC)、醋酸乙烯酯-乙烯共聚物可再分散乳胶粉黏结剂(VAE)、羟丙基甲基纤维素保水剂(HPMC)和骨胶缓凝剂(BG)对磷建筑石膏具有较好的适应性，可分别用于改善磷建筑石膏的绝干强度、黏结强度、保水性能及延长其凝结时间；PC和VAE能改善磷建筑石膏硬化体内部晶体结构的致密性，而BG、HPMC则使磷建筑石膏硬化体结构更加疏松。

Modification and Mechanism of Phosphorus Building Gypsum Using Admixtures

Preparation of phosphorus building gypsum (PBG) products is an important way for the resource utilization of phosphogypsum, and the appropriate modification technology is the key to ensure the industrialization of PBG products. PBG was modified by three water reducers, three retarders, two binders and two water retaining agents respectively, the adaptability of admixture varieties to PBG was discussed, and the influence rules of admixture content on the properties of PBG were studied. Moreover, the modification mechanism of the optimized admixture on PBG was analyzed by scanning electron microscope. The results indicate that the polycarboxylate water reducer (PC), vinyl acetate ethylene copolymer redispersible polymer powder binder (VAE), hydroxypropyl methyl cellulose water retaining agent (HPMC) and bone glue retarder (BG) have good adaptability to PBG, and improve the dry strength, bond strength, water retention and prolong the setting time of PBG, respectively. PC and VAE improve the compactness of the internal crystal structure in the hardened PBG, while BG and HPMC make the structure of the hardened PBG more loose.