Abedi Mohammadmahdi, Fangueiro Raul, Correia António Gomes
Department of Civil Engineering, ISISE, University of Minho, 4800-058 Guimarães, Portugal.
Department of Mechanical Engineering, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal.
Nanomaterials (Basel). 2021 Apr 9;11(4):961. doi: 10.3390/nano11040961.
In this study, a self-sensing cementitious stabilized sand (CSS) was developed by the incorporation of hybrid carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) based on the piezoresistivity principle. For this purpose, different concentrations of CNTs and GNPs (1:1) were dispersed into the CSS, and specimens were fabricated using the standard compaction method with optimum moisture. The mechanical and microstructural, durability, and piezoresistivity performances, of CSS were investigated by various tests after 28 days of hydration. The results showed that the incorporation of 0.1%, 0.17%, and 0.24% CNT/GNP into the stabilized sand with 10% cement caused an increase in UCS of about 65%, 31%, and 14%, respectively, compared to plain CSS. An excessive increase in the CNM concentration beyond 0.24% to 0.34% reduced the UCS by around 13%. The addition of 0.1% CNMs as the optimum concentration increased the maximum dry density of the CSS as well as leading to optimum moisture reduction. Reinforcing CSS with the optimum concentration of CNT/GNP improved the hydration rate and durability of the specimens against severe climatic cycles, including freeze-thaw and wetting-drying. The addition of 0.1%, 0.17%, 0.24%, and 0.34% CNMs into the CSS resulted in gauge factors of about 123, 139, 151, and 173, respectively. However, the Raman and X-ray analysis showed the negative impacts of harsh climatic cycles on the electrical properties of the CNT/GNP and sensitivity of nano intruded CSS.
在本研究中，基于压阻原理，通过掺入混合碳纳米管（CNT）和石墨烯纳米片（GNP）开发了一种自传感水泥稳定砂（CSS）。为此，将不同浓度的CNT和GNP（1:1）分散到CSS中，并采用标准压实方法和最佳含水量制作试件。在水化28天后，通过各种试验研究了CSS的力学性能、微观结构、耐久性和压阻性能。结果表明，与普通CSS相比，在含10%水泥的稳定砂中掺入0.1%、0.17%和0.24%的CNT/GNP，其无侧限抗压强度（UCS）分别提高了约65%、31%和14%。当CNM浓度超过0.24%至0.34%过度增加时，UCS降低了约13%。添加0.1%的CNM作为最佳浓度，增加了CSS的最大干密度，同时导致最佳含水量降低。用最佳浓度的CNT/GNP增强CSS，提高了试件的水化速率和对包括冻融和干湿循环在内的恶劣气候循环的耐久性。在CSS中添加0.1%、0.17%、0.24%和0.34%的CNM，其应变片系数分别约为123、139、151和173。然而，拉曼光谱和X射线分析表明，恶劣气候循环对CNT/GNP的电学性能和纳米侵入CSS的灵敏度有负面影响。
