Electrical and piezoresistive properties of cement composites with carbon nanomaterials

Abstract

This study investigates the effect of nanomaterials on the piezoresistive sensing capacity of cement-based composites. Three different nanomaterials—multi-walled carbon nanotubes, graphite nanofibers, and graphene oxide—were considered along with a plain mortar, and a cyclic compressive test was performed. Based on a preliminary test, the optimum flowability was determined to be 150 mm in terms of fiber dispersion. The electrical resistivity of the composites substantially decreased by incorporating 1 wt% multi-walled carbon nanotubes, but only slightly decreased by including 1 wt% graphite nanofibers and graphene oxide. This indicates that the use of multi-walled carbon nanotubes is most effective in improving the conductivity of the composites compared to the use of graphite nanofibers and graphene oxide. The fractional change in resistivity of the composites with nanomaterials exhibited similar behavior to that of the cyclic compressive load, but partial reversibility in fractional change in resistivity was obtained beyond 60% of the peak load. A linear relationship between the fractional change in resistivity and cyclic compression strain (up to 1500 με) was observed in the composites with multi-walled carbon nanotubes, and the gauge factor was found to be 166.6. It is concluded that cement-based composites with 1 wt% multi-walled carbon nanotubes can be used as piezoresistive sensors for monitoring the stress/strain generated in concrete structures.

Preparation and Characterization of Polypropylene/Carbon Nanotubes (PP/CNTs) Nanocomposites as Potential Strain Gauges for Structural Health Monitoring

“…However, a direct comparison is difficult because the strain sensing ability is affected by several parameters: testing mode (compression and tension) [80], load rate [81], conductive filler (CNF, CNT etc) [82], cementitious material (paste, mortar or concrete) [25], etc. Nevertheless, it is evident that the GF for PP/CNT-5 and PP/CNT-7 at 0.20% of strain is higher than the GF of most of the previous published works here used as comparison ( Figure 14) [19,25,80,[82][83][84][85][86][87][88][89][90][91]. Moreover, PP/CNT-5 nanocomposites at 0.40% of strain have the highest GF among the compared works ( Figure 14) [19,25,80,[82][83][84][85][86][87][88][89][90][91][92][93][94].…”

Self-sensing Properties of Concrete with Electric Arc Furnace Slag and Steel Fiber

“…전도성재료를 혼입한 시멘트기반 복합재료의 자기센싱 특성을 평가하기 위하여 다음과 같은 저항변화율(Fractional change in resistivity, FCR)이 사용되고 있다 (Lee et al, 2017;Yoo, You, Youn, et al, 2018).…”

“…여기서   와   는 각각 시작점에서의 저항 그리고 하중이 변화함에 따라 측정된 저항을 의미하고,   과   는 시작점에 서의 비저항 그리고 하중변화에 따른 비저항을 나타낸다. 하중이 가해지는 과정에서 발생하는 부재의 길이 변화가 무시할 만큼 작은 경우 저항변화율은 비저항 변화율과 같다 고 볼 수 있으며, 본 연구에서는 이 저항변화율을 적용하였다 (Yoo, You, Youn, et al, 2018 Yoo, You, Youn, et al, 2018 (Lee et al, 2017;Yoo, You, Youn, et al, 2018…”

“…여기서 는 비저항(Electrical resistivity), 은 저항 (Resistance), 는 매트릭스와 전극의 접촉면적, 은 전위차 를 측정하는 내부 두 전극사이 거리를 의미한다(Yoo, You, Youn, et al, 2018). LCR 미터로 측정된 저항 값을 위 식에 대입하여 비저항을 계산 할 수 있으며, 전기전도성(Electrical conductivity)은 비저항의 역수이다.…”

Piezoresistive Carbon Foams in Sensing Applications

“…Such a good mechanical diversity is particularly important since the optimal transfer of strain or displacement from the object to the sensor device requires soft (or stiff) matrices for large (small) displacements or deformations of soft (stiff) objects. The gauge factors of soft composites is typically low or moderate (between 1 and 10) but allow good analysis of large strains of up to several tens of percentages, whereas hard composites such as those of epoxy or cement have GF values even above 50 (Chiacchiarelli et al, 2013;Yoo et al, 2018) which can be exploited in low strain regimes.…”