Kong Chuiyuan, Zhou Bin, Guo Rongxin, Yan Feng, Wang Rui, Tang Changxi
Yunnan Key Laboratory of Disaster Reduction in Civil Engineering, Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology, Kunming 650500, China.
Yunnan Transportation Development Consulting Co., Ltd., Kunming 650100, China.
Materials (Basel). 2023 Jun 23;16(13):4549. doi: 10.3390/ma16134549.
Based on the physical and chemical properties of red sandstone (RS), RS is used to produce composite cementitious materials. The flowability, mechanical strength, and micromechanics of a red sandstone-cement binary cementitious material (RS-OPC) were investigated as functions of the amount of RS replacing the cement (OPC). Additionally, the feasibility of producing red sandstone-phosphogypsum-cement composite materials (RS-PG-OPC) using the phosphogypsum (PG)- enhanced volcanic ash activity of RS was investigated. The products of hydration and microstructures of RS-OPC and RS-PG-OPC were analyzed by XRD, FTIR, TG-DTG, and SEM. RS enhanced the flowability of RS-OPC relative to the unmodified cement slurry but lowered its mechanical strength, according to the experiments. When the quantity of OPC replaced was greater than 25%, the compressive strength after 28 days was substantially reduced, with a maximum reduction of 78.8% (RS-60). The microscopic mechanism of RS-OPC suggested that the active SiO in the RS can react with Ca(OH) to produce C-S-H but can only utilize small quantities of Ca(OH), confirming the low volcanic ash activity of RS. RS was responsible for dilution and filling. The incorporation of 5% PG into RS-PG-OPC slowed the hydration process compared with RS-OPC without PG but also increased the flowability and aided in the later development of the mechanical strength. This was primarily because the addition of PG provided the system with sufficient Ca and SO to react with [Al(OH)6] to form ettringite (AFt), therefore accelerating the dissolution of Al in RS to generate more AFt and C-(A)-S-H gels. To some extent, this excites the volcanic ash of RS. Therefore, if there is an abundance of waste RS in the region and a lack of other auxiliary cementitious materials, a sufficient quantity of PG and a finely powdered waste RS component can be used to replace cementitious materials prepared with OPC to reduce the mining of raw OPC materials.
基于红砂岩（RS）的物理和化学性质，红砂岩被用于生产复合胶凝材料。研究了红砂岩-水泥二元胶凝材料（RS-OPC）的流动性、力学强度和微观力学性能与取代水泥（OPC）的红砂岩用量之间的关系。此外，还研究了利用磷石膏（PG）增强红砂岩火山灰活性来生产红砂岩-磷石膏-水泥复合材料（RS-PG-OPC）的可行性。通过XRD、FTIR、TG-DTG和SEM对RS-OPC和RS-PG-OPC的水化产物和微观结构进行了分析。实验表明，相对于未改性的水泥浆体，红砂岩提高了RS-OPC的流动性，但降低了其力学强度。当OPC取代量大于25%时，28天后的抗压强度大幅降低，最大降幅为78.8%（RS-60）。RS-OPC的微观机理表明，红砂岩中的活性SiO能与Ca(OH)反应生成C-S-H，但只能消耗少量的Ca(OH)，这证实了红砂岩的火山灰活性较低。红砂岩起到了稀释和填充的作用。与不含PG的RS-OPC相比，在RS-PG-OPC中掺入5%的PG减缓了水化过程，但也提高了流动性，并有助于后期力学强度的发展。这主要是因为PG的加入为体系提供了足够的Ca和SO与[Al(OH)6]反应生成钙矾石（AFt），从而加速了红砂岩中Al的溶解，生成更多的AFt和C-(A)-S-H凝胶。在一定程度上，这激发了红砂岩的火山灰活性。因此，如果该地区有大量废弃红砂岩且缺乏其他辅助胶凝材料，则可以使用足够量的PG和细粉状的废弃红砂岩组分来替代用OPC制备的胶凝材料，以减少原生OPC材料的开采。
