A comparative investigation on the effects of nanocellulose from bacteria and plant-based sources for cementitious composites
A comparative investigation on the effects of nanocellulose from bacteria and plant-based sources for cementitious composites
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DOI：
10.1016/j.cemconcomp.2021.104316
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发表时间：
2021-11-05
影响因子：
10.5
通讯作者：
Shah, Surendra
中科院分区：
文献类型：
--
作者：
Haque, Muhammad Intesarul;Ashraf, Warda;Shah, Surendra
由于纤维素纳米材料的高拉伸强度和吸湿特性，最近人们对它们的兴趣日益浓厚。本研究比较了两种不同类型的纤维素纳米材料，包括由木材产生的纤维素纳米纤维 (CNF) 和细菌纤维素 (BC)，对普通波特兰水泥 (OPC) 浆体的宏观、微观和纳米尺度性能的影响。监测了 CNF 和 BC 对水泥浆体水化、微观结构、抗压强度和抗折强度的影响。使用四种剂量的纳米纤维素（0%、0.05%、0.1%和0.3%，按重量计）来制备水泥浆样品。研究发现，固化 90 天后，CNF 和 BC 的压缩强度和弯曲强度分别增加了 10% 和 55%。然而，只有 CNF 能够将砂浆样品因碱-硅反应引起的膨胀抑制 33%。在微观尺度上，CNF被发现加速早期水泥水化，而BC则延迟水泥水化。长期固化后，与对照批次相比，两种纳米纤维素类型的氢氧化钙 (CH) 含量较低，CSH 含量较高。统计纳米压痕表明，纳米纤维素的添加增加了水化水泥浆体中高密度CSH的相对量。压汞孔隙率计（MIP）和动态蒸气吸附（DVS）分析表明，两种类型的纳米纤维素都增加了纳米孔隙率并降低了微孔隙率。然而，与 BC 相比，CNF 的这种优势更为突出。
Interest in cellulosic nanomaterials has recently gained momentum due to their high tensile strength and hygroscopic properties. This study compared the effects of two different types of cellulose nanomaterials, including cellulose nanofibrils (CNF) produced from wood and bacterial cellulose (BC), on the macro, micro, and nano scale performances of Ordinary Portland Cement (OPC) paste. Effects of CNF and BC on cement paste hydration, microstructure, compressive strength, and flexural strength were monitored. Four dosages of nanocellulose (0%, 0.05%, 0.1% and 0.3%, by weight) were used to prepare cement paste samples. Both CNF and BC were found to increase compressive strengths and flexural strengths by 10% and 55%, respectively, after 90 days of curing. However, only CNF was able to suppress the expansion of mortar samples due to the alkali-silica reaction by 33%. At the microscale, CNF was found to accelerate the early age cement hydration, whereas BC delayed cement hydration. Both nanocellulose types resulted in lower calcium hydroxide (CH) and higher CSH contents compared to the control batch after long-term curing. Statistical nanoindentations showed that the additions of nanocellulose increase the relative amounts of high-density CSH in the hydrated cement paste. The mercury intrusion porosimeter (MIP) and dynamic vapor sorption (DVS) analyses indicated that both types of nanocellulose increase the nanoporosity and reduced the microporosity. However, such advantages were more prominent in the case of CNF compared to the BC.