Gao Yuxin, Qin Jihui, Li Zhen, Jia Xingwen, Qian Jueshi
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China.
Materials (Basel). 2023 Feb 21;16(5):1760. doi: 10.3390/ma16051760.
Creep deformation is an important aspect of magnesium phosphate cement (MPC) used as a structural material. In this study, the shrinkage and creep deformation behaviors of three different MPC concretes were observed for 550 days. The mechanical properties, phase composition, pore structure, and microstructure of MPC concretes after shrinkage and creep tests were investigated. The results showed that the shrinkage and creep strains of MPC concretes stabilized in the ranges of -140 to -170 με and -200 to -240 με, respectively. The low water-to-binder ratio and the formation of crystalline struvite were responsible for such low deformation. The creep strain had almost no effect on the phase composition; however, it increased the crystal size of struvite and reduced the porosity, especially the volume of pores with diameters <20 nm and >200 nm. The modification of struvite and densification of microstructure led to an improvement in both compressive strength and splitting tensile strength.
徐变变形是用作结构材料的磷酸镁水泥（MPC）的一个重要方面。在本研究中，对三种不同的MPC混凝土的收缩和徐变变形行为进行了550天的观测。研究了收缩和徐变试验后MPC混凝土的力学性能、相组成、孔结构和微观结构。结果表明，MPC混凝土的收缩应变和徐变应变分别稳定在-140至-170 με和-200至-240 με范围内。低水胶比和结晶鸟粪石的形成是造成这种低变形的原因。徐变应变对相组成几乎没有影响；然而，它增加了鸟粪石的晶体尺寸并降低了孔隙率，特别是直径<20 nm和>200 nm的孔隙体积。鸟粪石的改性和微观结构的致密化导致抗压强度和劈裂抗拉强度均有所提高。
