AN EXPERIMENTAL RESEARCH CONTRIBUTION TO THE USE OF CARBON NANOTUBES IN CEMENT COMPOSITES

Abstract

Indeed, cement is the second most widely used material after water, with annual global cement production exceeding 4 billion tons in each of the last ten years. Cementitious composites are favored in construction because of their high compressive strength, low cost of preparation, simple manufacturing method, and ease of usage. However, these composites have several drawbacks, including a low tensile capacity, poor deformation performance, and a high cracking tendency, all of which impact the long-term durability of constructions. Carbon nanotubes can reinforce at the nanoscale, which was not possible before. Experimental work was conducted, and specimens of cement pastes and mortars were cast toward testing the carbon nanotubes’ dispersion within the matrix. Carbon nanotubes are known for being very cohesive in their raw form and difficult to disperse into the water. Using ultrasonic energy (bath sonication) along with incorporating a polycarboxylate high-range water-reducing agent to disperse the multiwalled carbon nanotubes helped to achieve about an 18% gain in compressive strength for cement pastes compared to plain cement pastes. This observed gain in strength was evidence of reinforcement. Several aspects explain the restricted work of carbon nanotubes on the industrial scale, including the high price of carbon nanotubes, the absence of standards and confirmations, and the complexity of dispersions, mixing, transporting, casting, and sufficient curing procedures. However, these practical difficulties could be partially resolved by improving the dispersion method or using pre-dispersed carbon nanotubes, which would be encouraging and useful for further exploration at the laboratory scale and the industry floor.