Effect of Long-Term Low Temperature Environment on Microstructure and Mechanical Properties of Magnesium Oxychloride Cement

Abstract

Abstract: In order to reveal the durability of magnesium oxychloride cement (MOC) under long-term low temperature environment, the effect of freezing time on microstructure, phase composition and mechanical properties of MOC samples were investigated by SEM, MIP, XRD, TG-DSC, FT-IR and microcomputer electro-hydraulic servo pressure testing machine. The results show that MOC samples have good long-term low temperature frost resistance. After 12 months of long-term low temperature freezing experiment, the weight of MOC samples only increases by 0.9%. The microscopic morphology changes from fine needle-like and gel-like to thicker needle-like and gel-like block. The microporous structure does not change significantly, with the average pore diameter varying between 38 and 48 nm and the pore volume distribution (0.01 μm to 0.1 μm) fluctuating from 70% to 80%. The phase composition does not change significantly, and the content of the main strength phase 5Mg(OH)₂·MgCl₂·8H₂O (5·1·8 phase) only decreases by 3%. The mechanical properties decrease slightly, in which the compressive strength decreases by 3.4 MPa and the flexural strength decreases by only 2.6 MPa.

Key words: magnesium oxychloride cement, long-term low temperature environment, microstructure, mechanical property, frost resistance

CLC Number:

TQ172

CHANG Chenggong, AN Lingyun, DONG Jinmei, ZHENG Weixin, WEN Jing, YAN Fengyun, XIAO Xueying. Effect of Long-Term Low Temperature Environment on Microstructure and Mechanical Properties of Magnesium Oxychloride Cement[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2023, 42(12): 4208-4215.

References

[1] LI K, WANG Y S, YAO N N, et al. Recent progress of magnesium oxychloride cement: manufacture, curing, structure and performance[J]. Construction and Building Materials, 2020, 255: 119381.
[2] CHAN J. The development of magnesium oxychloride cement as repairing materials[J]. Structural Concrete, 2018, 19(5): 1290-1300.
[3] 刘盼, 常成功, 刘秀泉, 等. 粉煤灰掺量对氯氧镁水泥混凝土物理力学性能的影响[J]. 硅酸盐通报, 2021, 40(5): 1564-1572.
LIU P, CHANG C G, LIU X Q, et al. Influence of fly ash content on physical and mechanical properties of magnesium oxychloride cement concrete[J]. Bulletin of the Chinese Ceramic Society, 2021, 40(5): 1564-1572 (in Chinese).
[4] LI Z J, CHAU C K. Influence of molar ratios on properties of magnesium oxychloride cement[J]. Cement and Concrete Research, 2007, 37(6): 866-870.
[5] SGLAVO V M, DE GENUA F, CONCI A, et al. Influence of curing temperature on the evolution of magnesium oxychloride cement[J]. Journal of Materials Science, 2011, 46(20): 6726-6733.
[6] JIŘÍČKOVÁ A, LOJKA M, LAUERMANNOVÁ A M, et al. Synthesis, structure, and thermal stability of magnesium oxychloride 5Mg(OH)₂·MgCl₂·8H₂O[J]. Applied Sciences, 2020, 10(5): 1683.
[7] 邵化建, 李宗利, 肖帅鹏, 等. 干湿循环作用下混凝土力学性能及微观结构研究[J]. 硅酸盐通报, 2021, 40(9): 2948-2955.
SHAO H J, LI Z L, XIAO S P, et al. Mechanical properties and microstructure of concrete under drying-wetting cycles[J]. Bulletin of the Chinese Ceramic Society, 2021, 40(9): 2948-2955 (in Chinese).
[8] 范向前, 朱海堂, 胡少伟, 等. 强碱溶液环境下混凝土力学性能试验研究[J]. 华北水利水电学院学报, 2013, 34(1): 54-58.
FAN X Q, ZHU H T, HU S W, et al. Experimental research of mechanical properties of concrete subjected to strong alkaline solution attack[J]. Journal of North China Institute of Water Conservancy and Hydroelectric Power, 2013, 34(1): 54-58 (in Chinese).
[9] 南雪丽, 邵楷模, 杨兰兰, 等. 聚合物掺量对聚合物快硬水泥砂浆抗冻性的影响[J]. 兰州理工大学学报, 2016, 42(6): 134-137.
NAN X L, SHAO K M, YANG L L, et al. Influence of polymer additive amount on frost-resistance of polymer-modified fast-hardening cement mortars[J]. Journal of Lanzhou University of Technology, 2016, 42(6): 134-137 (in Chinese).
[10] 南雪丽, 邵楷模. 聚灰比对聚合物快硬水泥砂浆耐久性的影响[J]. 硅酸盐通报, 2016, 35(5): 1627-1631+1636.
NAN X L, SHAO K M. Influence of polymer cement ratio on durability properties of polymer modified rapid harding cement mortars[J]. Bulletin of the Chinese Ceramic Society, 2016, 35(5): 1627-1631+1636 (in Chinese).
[11] CHANG C G, AN L Y, DONG J M, et al. Study on deterioration process of magnesium oxychloride cement under the environment of dry-wet cycles[J]. Materials, 2023, 16(5): 1817.
[12] AN L Y, CHANG C G, YAN F Y, et al. Study on the deterioration mechanism of magnesium oxychloride cement under an alkaline environment[J]. Materials, 2023, 16(17): 5924.
[13] 刘盼. 氯氧镁水泥混凝土的抗盐卤侵蚀和抗冻性能研究[D]. 北京: 中国科学院大学, 2021: 85-106.
LIU P. Study on salt brine corrosion resistance and frost resistance of magnesium oxychloride cement concrete[D]. Beijing: University of Chinese Academy of Sciences, 2021: 85-106 (in Chinese).
[14] AIKEN T A, RUSSELL M, MCPOLIN D, et al. Magnesium oxychloride boards: understanding a novel building material[J]. Materials and Structures, 2020, 53(5): 1-16.
[15] PIVÁK A, PAVLÍKOVÁ M, ZÁLESKÁ M, et al. Foam glass lightened sorel’s cement composites doped with coal fly ash[J]. Materials, 2021, 14(5): 1103.
[16] ZÁLESKÁ M, PAVLÍKOVÁ M, PIVÁK A, et al. MOC doped with graphene nanoplatelets: the influence of the mixture preparation technology on its properties[J]. Materials, 2021, 14(6): 1450.
[17] CHANG C G, AN L Y, LIN R, et al. Effect of calcination temperature on mechanical properties of magnesium oxychloride cement[J]. Materials, 2022, 15(2): 607.
[18] 张建平, 彭生江, 李伟, 等. 混凝土低温性能的研究进展评述[J/OL]. 建筑结构, 2023: 1-10[2023-07-19]. https://kns.cnki.net/kcms/detail//11.2833.TU.20230106.1511.001.html.
ZHANG J P, PENG S J, LI W, et al. Literature review of low temperature performance of concrete[J/OL]. Building Structure, 2023: 1-10[2023-07-19]. https://kns.cnki.net/kcms/detail//11.2833.TU.20230106.1511.001.html (in Chinese).
[19] 天津化工研究院. 无机盐工业手册-上册[M]. 2版. 北京: 化学工业出版社, 1996.
Tianjin Research Institute of Chemical Industry. Inorganic salts industry manual: volume 1[M]. 2nd ed. Beijing: Chemical Industry Press, 1996 (in Chinese).
[20] KOGBARA R B, IYENGAR S R, GRASLEY Z C, et al. A review of concrete properties at cryogenic temperatures: towards direct LNG containment[J]. Construction and Building Materials, 2013, 47: 760-770.
[21] JIANG Z W, HE B, ZHU X P, et al. State-of-the-art review on properties evolution and deterioration mechanism of concrete at cryogenic temperature[J]. Construction and Building Materials, 2020, 257: 119456.
[22] 沈晓冬. 海洋工程水泥与混凝土材料[M]. 北京: 化学工业出版社, 2016.
SHEN X D. Cement and concrete for marine applications[M]. Beijing: Chemical Industry Press, 2016 (in Chinese).
[23] POWERS T C. A working hypothesis for further studies of frost resistance of concrete[J]. ACI Journal Proceedings, 1945, 41(1): 245-272.