Effect of Multiwalled Carbon Nanotubes on Mechanical Strength of Cement Paste

Abstract

This paper discusses the effect of multiwalled carbon nanotubes (CNT) on strength characteristics of hydrated portland cement paste. Various cement-CNT composites and an equivalent control mix were prepared by mixing 0.5, 0.75, and 1.0 percent CNTs (by weight of cement) to check the strength gain in portland cement composite material. Cylindrical specimens of size approximately 15.8 mm×31.6 mm were prepared for compressive strength and splitting-tensile strength tests to measure mechanical strength of composites. The specimens were tested at 7, 28, 60, 90, and 180 days of curing, and at least three samples were tested at each curing age. Results show an increase in compressive and splitting-tensile strengths in portland cement–CNT composites having CNT content of 0.5% by weight of portland cement. The increase in compressive and tensile strengths with respect to control mix were 15% and 36%, respectively, at 28 days curing age. Above 0.5% CNT content, the strength decreases. Scanning electron microscopy and transmission electron microscopy have also been carried out to check the microstructure bonding of the cement-CNT paste.