Studying the Incorporation of Multi-Walled Carbon Nanotubes in High-Performance Concrete

Abstract

The current work aimed to study nanomodified HPC with multi-walled carbon nanotubes (MWCNT). The effect of MWCNT concentration, from 0% to 0.6% of cement weight, was evaluated on HPC multi-level output properties, namely, the flowability, mechanical strength, electrical resistivity, and microstructure. In addition, a tentative, simplified, and more cost-effective method based on dispersion of a high-pH solution of hydroxide was also adapted to disperse the MWCNT before incorporation in fresh HPC mixtures. Adding 0.2–0.6% MWCNT reduced HPC workability even with a higher superplasticiser dosage. The electrical resistivity was 484.58 Ω m for the HPC without MWCNT at 28 days of curing, while the samples with 0.2%, 0.4%, and 0.6% MWCNT presented 341.41 Ω m, 363.44 Ω m, and 360.34 Ω m, respectively. The use of 0.2–0.6% MWCNT in HPC decreased the flexural and compressive strength by 20% and 30%, respectively. The HPC performance decrease with MWCNT seemed to be related to relatively significant agglomerations of the long MWCNTs, namely, in HPC-0.6% samples. New developments are needed to state a simple and cost-effective dispersion method for MWCNT incorporation in HPC. In addition, smaller dosages of MWCNT are suggested for future research works.