Modification of waste fluorgypsum and its applications as a cement retarder

Abstract

The waste fluorgypsum was modified and applied as a cement retarder. The main chemical composition and mineral structure of the waste fluorgypsum were analyzed. Scanning electron microscopy (SEM) and eight-channel micro-calorimeter (TAM Air) were employed to analyze the changes in morphology and study the application performance of the modified fluorgypsum, respectively. Experimental results indicate that the flexural strength and compressive strength of the modified fluorgypsum are roughly equal to those of the natural gypsum. The morphology of the crystal of the fluorgypsum changes from block particle into trimetric short column. The fluorgypsum crystals stagger mutually and improve the strength of the hardened body. The modified fluorgypsum as cement retarder could delay the hydration, reduce the heat of the hydration and make the setting time, volume stability, and the SO3 content of the cement meet the national standards. The modified fluorgypsum is a good substitute for the natural gypsum.

Keywords

waste fluorgypsum / modified technology / hydration heat / cement retarder / application performance

References

[1] FengQ.-b., WangJ.-h., ZhangX., WangL.-l., ChenY.-liang.. Study on comprehensive utilization of fluorgypsum [J]. Non-Metallic Mines, 2010, 33(3): 36-38

[2] JiangX.-hu.. The application status and analysis of fluorine gypsum [J]. Shanxi Architecture, 2008, 34(20): 161-162

[3] LiR.-yi.. Exploration and practice of comprehensive utilization of fluorgypsum residue [J]. Safety and Environmental Engineering, 2006, 13(1): 55-58

[4] LiR.-y., YuR.-g., ChenJ.-p., ChenX.-guang.. The comprehensive utilization of fluorgypsum residue in building material [J]. Inorganic Chemicals Industry, 2005, 37(12): 43-46

[5] XU Qing. Comprehensive utilization discussion on fluorine gypsum of fluorid salt factory [J]. Light Metal, 2000(10): 12–15. (in Chinese)

[6] ZHU Xiao-li, YANG Xiao-wen. Experiment on using fluorine gypsum as retarder instead of natural gypsum [J]. Journal of Tangshan Polytechnic College, 1999(4): 29–31. (in Chinese)

[7] TianJ.-cheng.. Study on comprehensive utilization of fluorgypsum [J]. Journal of Xuzhou Engineering College, 2005, 20(1): 104-107

[8] YANG Miao, GUO Zhao-hui, WEI Xiao-ying, XIAO Xi-yuan. Modification and comprehensive utilization of fluorgypsum [J]. Organo-Fluorine Industry, 2010(1): 9–41, 21. (in Chinese)

[9] YanP.-y., YangW.-yan.. The cementitious binder derived with fluorogypsum and low quality of fly ash[J]. Cem Concr Res, 2000, 30(2): 275-280

[10] YangX.-y., MuS.-b., WangJ.-hua.. Modification of fluor-gypsum and its application as a cement retarder [J]. China Cement, 2006, 50(6): 52-54

[11] KovlerK.. Strength and water absorption for gypsum cement-silica fume blends of improved performance [J]. Adv Cem Res, 1998, 10(2): 81-92

[12] YuD.-g., YangX.-y., YangS.-z., ZhangL.-ying.. A research on the properties and microstructure of hemihydrate gypsum [J]. Journal of WuHan University of Technology, 2006, 28(5): 27-29

[13] RahhalV., CabreraO., TaleroR., DelgadoA., PedrajasC.. C₄AF ettringite and calorific synergic effect contribution [J]. J Therm Anal Calorim, 2010, 100(1): 57-63

[14] KjellsenK. O., DetwillerR. J., GjorvO. E.. Development of microstructures in plain cement pastes hydrated at different temperatures [J]. Cem Conc Res, 1991, 21(1): 179-189

[15] TanG.-z., WuJ.-h., FanB.-s., JiangBin.. Effect of CaCO₃ on hydration characteristics of C3A [J]. J Cent South Univ Technol, 2010, 17(5): 1028-1035

[16] KjellsenK. O., DetwiterR. J.. Reaction kinetics of Portland cement mortars hydrated at different temperatures[J]. Cem Concr Res, 1992, 22(1): 112-120

[17] SemsiY., Gözde InanS.. The effect of cylindrical specimen size on the compressive strength of concrete [J]. Build Environ, 2007, 42(6): 2417-2420

[18] Al-NoaimiK. K., El-HosinyF. I., Abo-El-EneinS. A.. Thermal and pore structural characteristics of polymer-impregnated and superplasticized cement pastes [J]. J Therm Anal Calorim, 2000, 61(1): 173-180

[19] PacewskaB., BlonkowskiG., WilińskaI.. Investigations of the influence of different fly ashes on cement hydration [J]. J Therm Anal Calorim, 2006, 86(1): 179-186

[20] YanP.-y., YangW.-y., QinX., YouYi.. Microstructure and properties of the binder of fly ash-fluorogypsum-Portland cement [J]. Cem Concr Res, 1999, 29(3): 349-354

[21] YanP.-y., YouYi.. Hydraulic properties of the binder consisting of fluorgypsum and fly ash under different curing conditions [J]. Journal of the Chinese Ceramic Society, 1998, 26(6): 689-694