Nie Yanfeng, Lu Jingzhou, Liu Zhiyong, Meng Dan, He Zhihai, Shi Jinyan
School of Civil Engineering, Yantai University, Yantai 264005, China.
School of Civil Engineering, Yantai University, Yantai 264005, China.
Sci Total Environ. 2022 Nov 25;849:157871. doi: 10.1016/j.scitotenv.2022.157871. Epub 2022 Aug 8.
Magnesium oxychloride cement (MOC) has received extensive attention as an eco-friendly cement, but its poor water resistance limits its engineering applications. In this study, MOC mixture (MOCM) was modified with 10-50 % rice husk ash (RHA) (wt% of MgO), and the development of their fresh properties, mechanical strength and microstructure was investigated. The results show that the incorporation of RHA to MOCM increases the setting time of the mixture and reduces its flowability. Due to the fine particle size and high reactivity of RHA, the incorporation of an appropriate amount of RHA to MOCM improves the matrix compactness, thereby enhancing the compressive strength of the samples. Although the microstructure of MOCM deteriorates and the strength decreases after immersion in water, the strength retention coefficient of MOCM with 50 % RHA increases by 24.57 % compared with that of plain MOCM. The incorporation of RHA not only reduces the relative content of magnesium oxide in MOCM, but also generates Mg-Cl-Si-H gel, which is beneficial to improve the water resistance of MOCM. Meanwhile, with the increase of RHA content, the carbon emission of MOCM also decreases. Compared with other modification methods, RHA-modified MOCM performs better in terms of water resistance, environmental benefits and strength enhancement.
氯氧镁水泥（MOC）作为一种生态友好型水泥受到了广泛关注，但其耐水性较差限制了其工程应用。在本研究中，采用10% - 50%的稻壳灰（RHA）（占MgO的重量百分比）对MOC混合料（MOCM）进行改性，并研究了其新拌性能、力学强度和微观结构的发展。结果表明，向MOCM中掺入RHA会增加混合料的凝结时间并降低其流动性。由于RHA的粒径细且反应活性高，向MOCM中掺入适量的RHA可改善基体密实度，从而提高样品的抗压强度。虽然MOCM在水中浸泡后微观结构恶化且强度降低，但掺入50% RHA的MOCM的强度保留系数相比纯MOCM提高了24.57%。掺入RHA不仅降低了MOCM中氧化镁的相对含量，还生成了Mg-Cl-Si-H凝胶，这有利于提高MOCM的耐水性。同时，随着RHA含量的增加，MOCM的碳排放也降低。与其他改性方法相比，RHA改性的MOCM在耐水性、环境效益和强度增强方面表现更好。
