乳酸石膏制备α-半水石膏的分散性与结晶性工艺研究

Dispersibility and Crystallinity of α-Hemihydrate Gypsum Prepared by Lactic Acid Gypsum

以乳酸石膏为原料,采用加压水溶液法制备α-半水石膏(α-HH),用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)和激光粒度仪对制备的样品进行了表征,通过抗折强度测试仪测试α-半水石膏样品的2 h抗折强度。研究了有机酸含量对α-半水石膏晶体形貌和结晶性的影响,以及丙三醇含量对α-半水石膏晶体分散性与结晶性的影响。结果显示,添加0.11 wt.%有机酸制备得到的α-半水石膏,其晶体平均粒径为29.36μm,长径比接近1,结晶性较高,2 h抗折强度为5.68MPa;在添加0.11 wt.%有机酸基础上通过掺入1.40 g丙三醇改善了晶体的分散性,促进晶体发育更加完整,结晶性进一步提升,得到了2 h抗折强度为6.47 MPa的α-半水石膏。

Hemihydrate gypsum(α-HH)with excellent dispersibility and crystallinity was prepared by using a pressurized aqueous solution method with lactic acid gypsum as the raw material.The as-prepared products were characterized by using X-ray diffraction(XRD),field-emission scanning electron microscopy(FESEM)and laser particle size analysis(LPS).The 2 h flexural strength of the α-hemihydrate gypsum product was evaluated by using a flexural strength tester.Effects of organic acid content on crystal morphology and crystallinity,glycerol content on crystal dispersibility and crystallinity ofα-high strength gypsum were studied and discussed.It was found that the product obtained by adding 0.11 wt.% modifier possessed a high crystallinity,an average crystal size 29.36μm and an average aspect ratio of about 1,while the flexural strength of the sample formed from these gypsum binders after 2 h hardening reached 5.68 MPa.Based on these processing parameters,the presence of 1.40 g glycerol improved the crystal dispersibility and crystalline integrity,which resulted inα-HH with a flexural strength(2 h hardening)of 6.47 MPa.