Effect of Multi-Walled Carbon Nanotubes on Mechanical Properties of Concrete

Abstract

The main goal of this paper is to study the effect of different concentrations of long multi-walled carbon nanotubes (MWCNTs) and short MWCNTs on the mechanical properties of concrete (compressive strength, splitting tensile strength, flexural strength and static modulus of elasticity).Ultrasonic pulse velocity test was also used to evaluate the porosity of concrete nanocomposite. 81 specimens with MWCNTs of (0.03%, 0.045%, and 0.06%) by weight of dry cement were tested after 28 days of curing. Dispersion of MWCNTs was achieved by using Ultrasonic Liquid Processors with surfactant. Scanning electron microscopy SEM images for micro-crack bridging was conducted to examine the bonding between MWCNTs and the cement paste. Test results showed that the addition of very low concentrations of MWCNTs led to a reduction in the porosity of concrete composite and significant increase in the amount of high stiffness C-S-H gel. Specimens reinforced with (0.03% short CNT, 0.03% and 0.045% long CNT) showed an increase in density about (1.63%, 0.82%) respectively. In general reinforcing concrete with MWCNTs led to enhance the mechanical properties of concrete nanocomposites compared to the reference samples.