Abstract: The foamed magnesium oxysulfate cement (FMOSC) samples prepared by the composite modification and single-admixture modification of sodium dihydrogen phosphate (SDP) and sodium stearate (SS) were compared. The effect of compound modifier on dry density, porosity, pore structure, pore size distribution, compressive strength and softening coefficient of FMOSC were studied. The phase composition and microscopic morphology of hydration product were studied by X-ray diffraction, infrared spectra and scanning electron microscopy. The results show that SDP and SS have a slight influence on the dry density and porosity of the sample, the pore structure and pore size distribution are optimized, and the compressive strength and softening coefficient are more than two times higher than before modification by composite modification. In the meantime, the effect of the composite modification is better than that of single modification. The main hydrate product of FMOSC is Mg(OH)2 after the addition of SS and 517 phase when the SDP have been introduced. It is indicated that the H2PO4- can adsorb on the surface of hydrated magnesium oxide, inhibiting the formation of Mg(OH)2 and promoting the formation of 517 crystal nucleus. During the self-assembly process of crystal nucleus to form 517 crystal phase, the C17H35COO- adsorbed on the surface of crystal nucleus and affected the morphology of 517 crystal. Under the double action of SDP and SS, the FMOSC with advantages of lightweight, high strength and excellent water resistance have been prepared.
1 Shi J Y, Liu Y C, Liu B J, et al.Advances in Materials Science and Engineering, 2019, 2019(4). 2 Tan X J, Chen W Z, Hao Y G, et al. Advances in Materials Science and Engineering, 2014, 2014(8), 1. 3 Amran Y H M, Farzadnia N, Abang Ali A A. Construction and Building Materials, 2015, 101, 990. 4 Liu Z W, Zhao K, Hu C, et al. Advances in Materials Science and Engineering, 2016, 2016(11), 1. 5 Zhou X X, Yang Z Z, Xu Y J, et al. Materials Reports A: Review Papers, 2019, 33(8), 2546(in Chinese). 周薛霞, 杨赞中, 徐艳娇,等. 材料导报:综述篇, 2019, 33(8), 2546. 6 Luo X R, Fan W Q, Li C Q, et al. Journal of the Chinese Ceramic Society, 2020, 48(2), 222 (in Chinese). 罗学如, 范文强, 李春庆,等. 硅酸盐学报, 2020, 48(2), 222. 7 Ye Q Q, Han Y F, Zhang S F, et al.Journal of Hazardous Materials, 2020, 383, 121099. 8 Li Q Y, Zhang L C, Gao X J, et al.Construction and Building Materials, 2020, 230, 116990. 9 Wu C Y, Yu H F, Zhang H F, et al. Materials and Structures, 2015, 48(4), 907. 10 Wang N, Yu H F, Bi W L, et al.Construction and Building Materials, 2018, 169, 697. 11 Wu C Y. Fundamental theory and civil engineering application of basic magnesium sulfate cement. Ph.D. Thesis, Qinghai Institute of Salt Lakes, Chinese Academy of Science, China, 2014 (in Chinese). 吴成友. 碱式硫酸镁水泥的基本理论及其在土木工程中的应用技术研究.博士学位论文,中国科学院研究生院(青海盐湖研究所), 2014. 12 Liu C, Luo J L, Li Y Q, et al.Construction and Building Materials, 2019, 228, 116798. 13 Wang L M, Feng K B, Chen X F. Journal of Functional Materials, 2015, 46(12), 12009 (in Chinese). 王路明, 冯扣宝, 陈雪霏. 功能材料, 2015, 46(12), 12009. 14 WB/T 1019-2002. Caustic burned magnesia for magnesium oxychloride cement products. Standards Press of China, China, 2002(in Chinese). WB/T 1019-2002.菱镁制品用轻烧氧化镁, 中国标准出版社, 2002. 15 Zhang C M, Deng D H. New Building Materials, 1995(2), 11 (in Chinese). 张传镁, 邓德华 .新型建筑材料, 1995(2), 11. 16 Xie Y, Li J, Lu Z Y, et al.Construction and Building Materials, 2018, 179, 207. 17 Zhang X, Huang T H, Zhang Y J, et al. Journal of Building Materials, 2015, 18(1), 177 (in Chinese). 张雄, 黄廷皓, 张永娟, 等. 建筑材料学报, 2015, 18(1), 177. 18 Wang F Z, Yang L, Guan L Y, et al. Journal of Wuhan University of Technology-Mater. Sci. Ed, 2015, 30(2), 331. 19 Hilal A A, Thom N H, Dawson A R.Construction and Building Materials, 2015, 85, 157. 20 Wen J, Yu H F, Li Y, et al. Journal of Wuhan University of Technology-Mater. Sci. Ed, 2014, 29(1), 114. 21 Runćevski T, Wu C Y, Yu H F, et al.Journal of the American Ceramic Society, 2013, 96(11), 3609. 22 Yang Y F, Wu X F, Hu G S, et al.Journal of Crystal Growth, 2008, 310(15), 3557. 23 Dang L, Nai X Y, Zhu D H, et al.Applied Surface Science, 2014, 317, 325. 24 Guo T, Wang H F, Yang H J, et al.Construction and Building Materials, 2017, 150, 844. 25 Fan H, Song X F, Xu Y X, et al.Applied Surface Science, 2019, 478, 594. 26 Liu C J, Zhao Q, Wang Y G, et al.Applied Surface Science, 2016, 360, 263. 27 Yuan Z T, Wang Y B, Han Y X, et al. Chinese Journal of Inorganic Chemistry, 2008, 2008(7), 1062(in Chinese). 袁致涛, 王宇斌, 韩跃新, 等. 无机化学学报, 2008, 2008(7), 1062. 28 Izaguirre A, Lanas J, Lvarez J I. Cement and Concrete Research, 2009, 39(11), 1095. 29 Atahan H, Jr C, Chae S, et al.Cement and Concrete Composites, 2008, 30(7), 566. 30 Ramachandran V S, Lowery M S, Wise T, et al.Materials and Structures, 1993, 26(7), 425. 31 Wu X X, Qi S S, Chang T T, et al. Bulletin of the Chinese Ceramic So-ciety, 2019,38(9), 2731(in Chinese). 吴潇潇, 岂珊珊, 常婷婷, 等. 硅酸盐通报, 2019, 38(9), 2731. 32 Xiao J F, Nai X Y, Gou S L, et al. Journal of Inorganic Materials, 2019, 34(11), 1181(in Chinese). 肖剑飞,乃学瑛,苟生莲,等. 无机材料学报, 2019, 34(11), 1181.