Lv Shenghua, Hu Haoyan, Zhang Jia, Luo Xiaoqian, Lei Ying, Sun Li
College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
College of Environment Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
Nanomaterials (Basel). 2017 Dec 18;7(12):457. doi: 10.3390/nano7120457.
Original graphene oxide (GO) nanosheets were prepared using the Hummers method and found to easily aggregate in aqueous and cement composites. Using carboxymethyl chitosan (CCS) as a dispersant, few-layered GO nanosheets (1-2 layers) were obtained by forming CCS/GO intercalation composites. The testing results indicated that the few-layered GO nanosheets could uniformly spread, both in aqueous and cement composites. The cement composites were prepared with GO dosages of 0.03%, 0.05% and 0.07% and we found that they had a compact microstructure in the whole volume. A special feature was determined, namely that the microstructures consisted of regular-shaped crystals created by self-crosslinking. The X-ray diffraction (XRD) results indicated that there was a higher number of cement hydration crystals in GO/cement composites. Meanwhile, we also found that partially-amorphous Calcium-Silicate-Hydrate (C-S-H) gel turned into monoclinic crystals. At 28 days, the GO/cement composites reached the maximum compressive and flexural strengths at a 0.05% dosage. These strengths were 176.64 and 31.67 MPa and, compared with control samples, their increased ratios were 64.87% and 149.73%, respectively. Durability parameters, such as penetration, freeze-thaw, carbonation, drying-shrinkage value and pore structure, showed marked improvement. The results indicated that it is possible to obtain cement composites with a compact microstructure and with high performances by introducing CCS/GO intercalation composites.
采用Hummers法制备了原始氧化石墨烯（GO）纳米片，发现其在水性和水泥复合材料中容易聚集。以羧甲基壳聚糖（CCS）为分散剂，通过形成CCS/GO插层复合材料获得了少层GO纳米片（1-2层）。测试结果表明，少层GO纳米片在水性和水泥复合材料中均能均匀分散。制备了GO用量分别为0.03%、0.05%和0.07%的水泥复合材料，发现其整体体积内具有致密的微观结构。确定了一个特殊特征，即微观结构由通过自交联形成的规则形状晶体组成。X射线衍射（XRD）结果表明，GO/水泥复合材料中水泥水化晶体的数量较多。同时，还发现部分非晶态的硅酸钙水化物（C-S-H）凝胶转变为单斜晶体。在28天时，GO/水泥复合材料在0.05%的用量下达到最大抗压强度和抗折强度。这些强度分别为176.64和31.67MPa，与对照样品相比，其提高比例分别为64.87%和149.73%。耐久性参数，如渗透、冻融、碳化、干燥收缩值和孔结构，均有显著改善。结果表明，通过引入CCS/GO插层复合材料，可以获得具有致密微观结构和高性能的水泥复合材料。
