Electrical resistivity and self-sensing properties of low-cement limestone calcined clay cement (LC3) mortar
Wenkui Dong, Ameer Hamza Ahmed, Marco Liebscher, Huanyu Li, Yipu Guo, Bo Pang, Mostafa Adresi, Wengui Li, Viktor Mechtcherine
Abstract
Dilutive effects of calcined clay and limestone in studied compositions and their impact on the potential contact point and piezoresistivity. • No significant differences in their electrical resistivity were found for the plain OPC, LC3-50, and LC3-25 mortars after 28 days of hydration. • Small dosage of rCF could not greatly enhance the conductivity of LC3 mortar until being dried. • Self-sensing cement-based sensor with ultra-low fibre content could help decrease the cost of sensors. • Two-probe method led to the continual growth of electrical resistivity when the polarization was remarkable. This study investigated the mechanical, electrical, and piezoresistive performances of mortars made with Ordinary Portland cement (OPC) and limestone calcined clay cement (LC 3 ), especially when reinforced with 0.1 wt% recycled carbon fibre (rCF) by weight of the binder. The results found that 0.1 wt% rCF failed to considerably enhance the electrical conductivity of OPC and LC 3 mortars during the curing period, but the enhancement became apparent when these composites were 1 day-dried. With the increasing cement replacement ratio and the introduction of rCF, the mechanical properties deteriorated because of the dilutive effects together with the fragility of rCF. The OPC and LC 3 mortars exhibited a certain degree of piezoresistivity under compression, which was amplified with added 0.1 wt% rCF. Additionally, the piezoresistive performance of the LC 3 mortar was better than that of the OPC mortar, regardless of the presence of rCFs. The sensing capacity of composites is greatly weakened in terms of flexural stress. In terms of the two-probe method, because of the contact resistance, the resistivity usually decreases under compression, which results in larger fractional changes in resistivity values. This study aims to develop a low conductivity self-sensing cement-based composites (SSCC) filled with small dosage of rCF.