Chen Qian, Chen Haiming, Wang Pengju, Chen Xiang, Chen Jie
School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, China.
Engineering Research Center of Underground Mine Construction, Ministry of Education, Anhui University of Science and Technology, Huainan 232001, China.
Materials (Basel). 2021 Oct 1;14(19):5751. doi: 10.3390/ma14195751.
The effect of the dosage of sulphur-containing tailings (STs) and curing temperature on the properties of M32.5 cement mortar was studied in this work. An experimental study was conducted to evaluate the effects of STs with different substitution ratios (0, 10%, 20%, 30%, 40%) on the compressive strength experiment, fluidity, expansion ratio, and pore structure of M32.5 cement mortar. The results showed that the addition of STs reduced the fluidity of mortar, and the fluidity decreased with the increase of the STs dosage. The compressive strength of mortars increased at a lower substitution rate (0~20%) but decreased at a higher substitution rate (>20%). Ettringite peaks and new sulfate peaks were found by X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) observation of the microstructure showed that a large number of hydrated products, such as ettringite, formed and filled in the interstitial space, which was conducive to the development of strength. The optimal STs replacement ratio of river sand was 10%. Then, the performance of mortar at curing temperatures of 23 ± 1, 40, 60, and 80 °C was further investigated under the optimal STs replacement ratio. Under high-temperature curing conditions, the early strength of M32.5 cement mortar with STs increased greatly, but the late strength decreased gradually with the increase in curing temperature. The early strength development of the mortar mainly depended on the high speed of hydration reaction, and the late strength variation was mainly affected by hydration products and the pore size distribution. After comprehensive consideration, the optimal curing temperature of M32.5 cement mortar with STs was 40 °C.
本研究考察了含硫尾矿（STs）掺量及养护温度对M32.5水泥砂浆性能的影响。通过试验研究了不同取代率（0、10%、20%、30%、40%）的STs对M32.5水泥砂浆抗压强度试验、流动性、膨胀率及孔结构的影响。结果表明，STs的加入降低了砂浆的流动性，且流动性随STs掺量的增加而降低。较低取代率（0~20%）时，砂浆抗压强度提高；较高取代率（>20%）时，砂浆抗压强度降低。通过X射线衍射（XRD）分析发现了钙矾石峰和新的硫酸盐峰。扫描电子显微镜（SEM）对微观结构的观察表明，大量水化产物如钙矾石生成并填充孔隙，有利于强度发展。河砂的最佳STs取代率为10%。然后，在最佳STs取代率下，进一步研究了23±1、40、60和80℃养护温度下砂浆的性能。在高温养护条件下，含STs的M32.5水泥砂浆早期强度大幅提高，但后期强度随养护温度升高逐渐降低。砂浆早期强度发展主要取决于水化反应速度快，后期强度变化主要受水化产物和孔径分布影响。综合考虑，含STs的M32.5水泥砂浆最佳养护温度为40℃。
