Effect of Dispersion of Carbon Nanotubes on Electrical Conductivity and Compressive Strength of CNT/Cement Composite

Abstract

Carbon nanotubes (CNTs) are promising nanomaterials due to their exceptional properties, including high electrical, mechanical, and stability characteristics. These advantageous features position CNTs as suitable candidates for diverse applications, particularly in additive formulations designed to enhance overall performance. One notable application is their use in cement composites to improve mechanical and electrical properties. However, the hydrophobic property of CNTs presents challenges for dispersion within the hydrophilic cement matrix. Consequently, methods have been developed to aid CNT dispersion in both water and cement matrices. In this thesis, Triton X-100 employed as a surfactant, was used to disperse CNTs in water using various ratios (0.5:1, 1:1, 1.5:1, and 2:1) in a CNT suspension. The dispersion of CNTs in suspension was characterized using UV-vis spectroscopy to determine the optimal ratio between Triton X and CNTs. Subsequently, conditions demonstrating effective CNT dispersion with Triton X-100, as identified from the UV-vis spectroscopy results, were applied and mixed with cement to form CNT/cement composites. The properties of these composites were analyzed by varying the ratio of Triton X-100 to CNTs (1:1, 1.5:1, and 2:1) and the amount of CNTs in the cement ratio (0.1 – 0.4 wt%). The properties of composite were investigated, including flowability, porosity, compressive strength, and electrical conductivity. Additionally, morphology and dispersion of CNTs within composites were further examined using scanning electron microscopy (SEM). From the results, the condition involving an increase in Triton X-100 while controlling CNT content significantly improved CNT dispersion within the composite. Furthermore, an increase in the CNT content under appropriate conditions enhanced compressive strength. The highest compressive strength at a curing time of 28 days, with the highest CNT dispersion value within the composite, was achieved with 2 g of CNTs and 1 g of Triton X-100 condition. The compressive strength of this condition surpassed the control condition by 21.77%. Moreover, the highest electrical conductivity was achieved in the composite with 4 g of CNTs and 1 g of Triton X-100, marking the highest CNT content condition in this study. This represents a substantial 44.30% improvement compared to the control condition at a curing time of 28 days.