May the Piezoresistivity of GNP-Modified Cement Mortar Be Related to Its Fractal Structure?
May the Piezoresistivity of GNP-Modified Cement Mortar Be Related to Its Fractal Structure?
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GNP改性水泥砂浆的压阻率可能与其分形结构有关？
DOI：
10.3390/fractalfract5040148
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发表时间：
2021-12-01
影响因子：
5.4
通讯作者：
Zhao, Weijian
中科院分区：
文献类型：
--
作者：
Dang, Nanxi;Tao, Jin;Zhao, Weijian
通过导电填料调节的水泥基复合材料的高压阻特性为开发自感知智能结构和建筑物提供了一种可行的途径。然而，其微观结构机制仍有待正确理解。在本研究中，对不同石墨烯纳米片（GNPs）掺量的水泥砂浆的压阻特性进行了研究，并通过电子扫描显微镜（SEM）和压汞法（MIP）对其微观结构进行了评估。引入了两种表面分形模型来解释MIP数据，以探索GNP改性水泥砂浆的多尺度分形结构。结果表明，由于GNPs的团聚，将GNPs掺入水泥砂浆会使断裂面变得粗糙。当GNP含量从0%增加到1%时，应变系数（GF）先升高后降低，在GNP = 0.1%和0.05%时观察到最佳压阻特性。最佳砂浆的GF值比参考砂浆高出50倍以上。宏观和微观分形区域的分形维数随GNP含量而变化。分析表明，微观区域的分形维数随GF值的增加先减小后增大。GNPs不仅影响水泥砂浆的分形结构，还改变了控制复合材料压阻特性的隧道效应和接触效应。
High piezoresistivity of cement-based composites tuned by conductible fillers provides a feasible way to develop self-sensing smart structures and buildings. However, the microstructural mechanisms remain to be properly understood. In the present work, the piezoresistivity of cement mortar with different dosages of graphene nanoplatelets (GNPs) was investigated, and the microstructure was assessed by electron scanning microscopy (SEM) and mercury intrusion porosimetry (MIP). Two surface fractal models were introduced to interpret the MIP data to explore the multi-scale fractal structure of the GNP-modified cement mortars. Results show that the incorporation of GNPs into cement mortar can roughen the fracture surfaces due to the GNPs’ agglomeration. Gauge factor (GF) rises and falls as GNP content increases from 0% to 1% with the optimal piezoresistivity observed at GNP = 0.1% and 0.05%. The GF values of the optimum mortar are over 50 times higher than those of the reference mortar. Fractal dimensions in macro and micro fractal regions change with GNP content. Analysis shows that the fractal dimensions in micro region decrease first and then increase with the increase of GF values. GNPs not only impact the fractal structure of cement mortar, but also alter the tunneling and contact effects that govern the piezoresistivity of composite materials.