Lu Liulei, Ouyang Dong, Xu Weiting
Department of Mechanics and Civil Engineering, Jinan University, Guangzhou 510632, China.
Research Center of Engineering Materials and Structural Durability, Jinan University, Guangzhou 510632, China.
Materials (Basel). 2016 May 27;9(6):419. doi: 10.3390/ma9060419.
In this work, the effect of the addition of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties and durability of ultra high strength concrete (UHSC) is reported. First, the MWCNTs were dispersed by a nano sand-mill in the presence of a surfactant in water. The UHSC specimens were prepared with various amounts of MWCNTs, ranging from 0% to 0.15% by weight of cement (bwoc). Results indicated that use of an optimal percentage of MWCNTs (0.05% bwoc) caused a 4.63% increase in compressive strength and a 24.0% decrease in chloride diffusion coefficient of UHSC at 28 days curing. Moreover, the addition of MWCNTs also improved the flexural strength and deformation ability. Furthermore, a field-emission scanning electron microscopy (FE-SEM) was used to observe the dispersion of MWCNTs in the cement matrix and morphology of the hardened cement paste containing MWCNTs. FE-SEM observation revealed that MWCNTs were well dispersed in the matrix and no agglomerate was found and the reinforcing effect of MWCNTs on UHSC was thought to be pulling out and microcrack bridging of MWCNTs, which transferred the load in tension.
在本研究中，报道了添加多壁碳纳米管（MWCNTs）对超高强混凝土（UHSC）力学性能和耐久性的影响。首先，在水中表面活性剂存在的情况下，通过纳米砂磨机分散MWCNTs。制备了含有不同量MWCNTs的UHSC试件，其含量范围为水泥重量的0%至0.15%（bwoc）。结果表明，使用最佳比例的MWCNTs（0.05% bwoc）可使UHSC在28天养护时的抗压强度提高4.63%，氯离子扩散系数降低24.0%。此外，添加MWCNTs还提高了抗弯强度和变形能力。此外，用场发射扫描电子显微镜（FE-SEM）观察了MWCNTs在水泥基体中的分散情况以及含MWCNTs的硬化水泥浆体的形态。FE-SEM观察表明，MWCNTs在基体中分散良好，未发现团聚现象，MWCNTs对UHSC的增强作用被认为是MWCNTs的拔出和微裂纹桥接，从而在拉伸时传递荷载。
