Effects of citric acid on hydration process and mechanical properties of thermal decomposed magnesium oxychloride cement

Abstract

In order to make full use of salt lake magnesium resources and improve the strength of the thermal decomposed magnesium oxychloride cement (TDMOC), the effects of citric acid on the hydration process and mechanical properties of TDMOC was studied. The hydration heat release at initial 24 h and strengths at 3, 7, and 28 days of TDMOC specimens were conducted. The hydration products and paste microstructure were analyzed by XRD, FT-IR and SEM, respectively. The results showed that citric acid can not only reduce the 24 h hydration heat release and delay the occurring time of second peak of TDMOC, but also produce more 5Mg(OH)₂·MgCl₂·8H₂O and less Mg(OH)₂ in hydration process of TDMOC. More perfect and slender crystals were observed in the microstructure of the TDMOC pastes with citric acid. The results demonstrated that citric acid as an additive of TDMOC can decrease the hydration heat release and increase the compressive strength and flexural strength of TDMOC. The possible mechanism for the strength enhancement was discussed.

Keywords

thermal decomposed magnesium oxychloride cement / citric acid / hydration heat / strength

References

[1] Wen J, Deng T, Wang S, . Caloric Evaporation Test for the Summer Salt Lake Brine in the Dongtaijilaier Salt Lake[J]. Journal of Salt and Chemical Industry, 2011, 40(1): 22-26.

[2] Ma Peihua Comprehensive Utilization of Salt Lake Resources [J]. Advance in Earth Sciences, 2000, 5(4): 365-374.

[3] Guo M, Li Q, Liu H, . The Exploitation and Utilization of Magnesium Resources in Salt Lakes[J]. Progress in Chemistry, 2009, 21(11): 2 358-2 364.

[4] Sorrel S On a New Magnesium Cement[J]. Comptes Rendus-Academie des sciences, 1867, 65: 102-105.

[5] Li Z, Chau C K Influence of Molar Ratios on Properties of Magnesium Oxychloride Cement[J]. Cem. Concr. Res., 2007, 37(6): 866-870.

[6] Ball M C Reactions of Compounds Occurring in Sorrel’s Cement [J]. Cem. Concr. Res., 1977, 7: 575-584.

[7] Tooper B, Cartz L Structure and Formation of Magnesium Oxychloride Sorel Cements[J]. Nat. Phys. Sci., 1966, 211: 64-66.

[8] Wen J, Yu H, Wu C, . Hydration Kinetic and Influencing Parameters in Hydration Process of Magnesium Oxychloride Cement[J]. Journal of the Chinese Ceramic Society, 2013, 5: 16-24.

[9] Cole W F, Demediuk T X-ray, Thermal and Dehydration Studies on Magnesium Oxychloride[J]. Australian Journal of Chemistry, 1955, 8(2): 234-251.

[10] Bilinski H, Matrovic B, Mazuranic C, . The Formation of Magnesium Oxychloride Phases in the Systems MgO-MgCl2-H₂O and NaOH-MgCl₂-H₂O[J]. J. Am. Ceram. Soc., 1984, 67(4): 266-275.

[11] Matkovic B, Young J F. Microstructure of Magnesium Oxychloride Cements [J]. Nature (London), Phys. Sci., 1973, 246-270

[12] Li Y, Yu H, Zheng L, . Compressive Strength of Fly Ash Magnesium Oxychloride Cement Containing Granite Wastes[J]. Construction and Building Materials, 2013, 38: 1-7.

[13] Li Y, Yu H, Dong J, . Reseach Development on Hydration Product, Phase Transformation and Water Resistance Evaluation Method of Magnesium Oxychloride Cement [J]. Journal of the Chinese Ceramics Society, 2013, 41(11): 1 465-1 471.

[14] Wen J, Yu H, Li Y, . Effects of H₃PO₄ and Ca(H₂PO₄)₂ on Mechanical Properties and Water Resistance of Thermally Decomposed Magnesium Oxychloride Cement[J]. J. Cent. South Univ., 2013, 20(12): 3 729-3 735.

[15] Yu Hongfa, Wen Jing, Dong Jinmei, et al. A New Magnesium Oxychloride Cement Mixing with Water Directly [P]. China patent, CN 102674725A, 2012-09-19

[16] Yuan Runzhang Cementitious Material Science[M], 1996 Wuhan Wuhan University of Technology Press

[17] Wang S, Du Y, Sun Q, . Study on Preparation of Magnesia Cement Raw Materials by Partial Thermal Decomposition of Hydrate Magnesium Chloride in Fluidized Bed [J]. Journal of Salt Lake Research, 2010, 18(1): 42-45.

[18] Sun Qingguo, Du Yongsheng, Wang Shidong, et al. The Prepared Method of Magnesia Cement by Partial Thermal Decomposition of Bischofite [P]. China patent, 200810150359.1, 2008-07-09

[19] Kontori E, Perraki T, Tsivilis S, . Zeolite Blended Cements: Evaluation of Their Hydration Rate by Means of Thermalanalysis [J]. J. Therm. Anal. Calorim., 2009, 96: 993-1 000.

[20] Miao C, Tian Q, Sun W, . Water Consumption of the Early-age Paste and the Determination of “Time-zero” of Selfdesiccation Shrinkage[J]. Cem. Concr. Res., 2007, 37: 1 496-1 501.

[21] Goñi S, Guerrero A Study of Alkaline Hydrothermal Activation of Belite Cements by Thermal Analysis[J]. J. Therm. Anal. Calorim., 2010, 99: 471-477.

[22] Janotka I, Mojumdar S C Thermal Analysis at the Evaluation of Concrete Damage by High Temperatures[J]. J. Therm. Anal. Calorim., 2005, 81: 197-203.

[23] Kjellsen K O, Detwiller R J, Gjorv O E Development of Microstructures in Plain Cement Pastes Hydrated at Different Temperatures [J]. Cem. Conc. Res., 1991, 21(1): 179-189.

[24] Sugimoto K, Dinnebier R E, Schlecht T Structure Determination of Mg₃(OH)₅Cl·4H₂O (F5 phase) from Laboratory Powder Diffraction Data and its Impact on the Analysis of Problematic Magnesia Floors [J]. Acta Crystallogr. Sect. B-Struct. Sci., 2007, 63: 805-811.

[25] Sglavo V, De Genua F, Conci A, . Influence of Curing Temperature on the Evolution of Magnesium Oxychloride Cement [J]. Journal of Materials Science, 2011, 46(20): 6 726-6 733.

[26] Bruker. Bruker AXS (2006)[M], 2006 Karlsruhe TOPAS Bruker AXS Inc

[27] Dhanapandian S, Gnanavel B Using Granite and Marble Sawing Power Wastes in the Production of Bricks: Spectroscopic and Mechanical Analysis[J]. Research Journal of Applied Sciences( Engineering and Technology), 2010, 2: 73-86.

[28] Xia S, Xing P, Gao Shiyang Studies on the Basic Compounds of Magnesia Cement: the Thermal Behavior of Magnesium Oxychlorides[J]. Thermochimica Acta, 1991, 183: 349-363.

[29] Salomão R, Pandolfelli V C Citric Acid as Anti-hydration Additive for Magnesia Containing Refractory Castables [J]. Ceramics International, 2011, 37(6): 1 839-1 842.