Morphology, crystal structure and hydration of calcined and modified anhydrite

Abstract

The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100°C causes anhydrite to disintegrate into smaller crystals, accompanied by a slight increase in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 min, respectively. The compressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material.

Keywords

anhydrite / morphology / crystal structure / curing / hydration / calcination / modification

References

[1] Luo HL, Chen JC, Li XQ, Zheng XY. Study on composite modification. Shandong Build. Mater., 2003, 24(4): 45

[2] Peng JH, Zhang JX, Bai L, Li Q. Hydration and hardening characteristics of anhydrite binder modified with slag. J. Tongji Univ. Nat. Sci., 2009, 37(7): 934

[3] Ohenoja K, Saari J, Illikainen M, Niinimaki J. Effect of the molecular structure of polymer dispersants on limestone suspension properties in fine grinding. J. Chem. Chem. Eng., 2013, 7, 606

[4] Yang XY, Mu SB, Qin KG. Effect of grinding method on activity of anhydrite. Bull. Chin. Ceram. Soc., 2004, 23(1): 50

[5] Zhang JX, Peng JH, Dong J, Bai L, Qu JD. Study on anhydrite activated by grinding and aid-grinding/dispersive action of water reducing agent. Non Metall. Mines, 2008, 31(6): 30

[6] Yang XY, Yang SZ, Chen WY. Study on the solubility and the structure of calcined anhydrite. J. Wuhan. Univ. Technol., 2000, 22(2): 21

[7] Fu YL, Li B, Cui P. Research on the technology of uniting calcining with acid-leaching for anhydrite. Appl. Chem. Ind., 2012, 41(1): 16

[8] Pan QX. Mechanism of the activation of fly ash by calcined anhydrite. New Build. Mater., 2001 9

[9] Peng JH, Dong J, Zhang JX, Bai L, Wan TZ. Dissolution and hydration performance of calcined anhydrite and its calcination activation mechanism. J. Build. Mater., 2010, 13(1): 111

[10] Wang FX. The influence of calcination temperature on the activity of anhydrite. Sichuan Water Conservancy, 2010 44

[11] Zhai HX, Chen FQ, Zhang XH. The influence of the activator on the hydration property of natural anhydrite. Acta Petrol. Mineral., 2011, 30(2): 301

[12] Peng JH, Zhang GH, Bai L, Zhang JX, Qu JD. Study on anhydrite binder activated by sulfate salt and modified with slag. Bull. Chin. Ceram. Soc., 2008, 27(4): 837

[13] Chen JC, Luo HL. Properties of anhydrite modified at different conditions. J. Chin. Ceram. Soc., 2005, 33(2): 249

[14] Yang M, Cao JX, Xie Y. Activation of anhydrite: II. Phosphogypsum by hemihydrate. J. Wuhan Univ. Technol., 2010, 82(18): 63

[15] Huang YH. Impact of water on physical and mechanical characteristics of anhydrite. Min. Technol., 2008, 8(6): 31