You Ilhwan, Yoo Doo-Yeol, Kim Sooho, Kim Min-Jae, Zi Goangseup
School of Civil, Environmental and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Korea.
Department of Architectural Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea.
Sensors (Basel). 2017 Oct 29;17(11):2481. doi: 10.3390/s17112481.
This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state.
本研究考察了含和不含碳纳米管（CNT）的超高性能纤维增强混凝土（UHPFRC）的电学性能和自传感能力。为此，首先评估了钢纤维含量、取向和孔隙水含量对不含CNT的UHPFRC电学性能和压阻性能的影响。然后，研究了CNT含量对UHPFRC在压缩和弯曲状态下自传感能力的影响。试验结果表明，较高的钢纤维含量、较好的纤维取向以及较多的孔隙水会导致UHPFRC具有更高的电导率。当添加足够高含量（体积分数为3%）的钢纤维时，纤维取向和干燥条件对电导率的影响变小。仅包含钢纤维不会使UHPFRC具有压阻性能。添加CNT显著提高了UHPFRC的电导率。在压缩状态下，CNT含量为0.3%或更高的UHPFRC具有由裂缝形成激活的自传感能力，并且包含更多的CNT可实现更好的传感能力。此外，当掺入0.3%的CNT时，UHPFRC的峰值前弯曲行为可通过电阻率的分数变化精确模拟。含CNT的UHPFRC在拉伸应力状态下的开裂前自传感能力比在压缩应力状态下更有效。
