Electrical resistance and compressive strength properties of cement composites using MWCNT dispersed in polycarboxylic acid superplasticizer

Multi-walled carbon nanotubes (MWCNTs) are among the most frequently utilized highly conductive materials in cementitious composites. However, numerous studies have reported that the hydrophobic nature of CNTs can lead to their aggregation upon exposure to water, subsequently inducing micro-defects within the cementitious matrix. This aggregation has been shown to degrade both the mechanical properties and durability of cement composites. Extensive research has been conducted to address this issue, with reports indicating that the incorporation of polycarboxylate-based superplasticizers, commonly employed in concrete, can mitigate CNT aggregation, thereby enhancing various performance aspects of cementitious composites. In this study, the electrical resistance and compressive strength of cementitious composites incorporating dispersed CNTs were evaluated, utilizing a polycarboxylate-based superplasticizer (PCE), a typical admixture for concrete, as a CNT dispersant.
The incorporation of carbon nanotubes (CNTs) dispersed with polycarboxylate (PCE) superplasticizer has been demonstrated to enhance the mechanical performance and electrical conductivity of cementitious composites, evidenced by an increase in 28-day compressive strength and a reduction in electrical resistance. Specifically, an optimal CNT content of 0.5 wt% was identified. It was observed that CNT concentrations exceeding 0.5 wt% led to a degradation in performance, primarily attributed to CNT agglomeration. For instance, at 0.75 wt% CNT content, the compressive strength was lower than that achieved with 0.5 wt%, while the electrical resistivity showed no significant difference. Similar trends were observed at a CNT content of 1.0 wt%.