Performance Evaluation of M40 Grade Concrete With GGBS, Fly Ash, and Carbon Nanotube Admixtures: A Comparative Study

Concrete, the most commonly used construction materials, encounters issues because of its substantial cement content, leading to environmental harm, alongside limitations in strength and durability. This study examines the mechanical and durability properties of M40 grade concrete modified with Ground Granulated Blast Furnace Slag (GGBS), Fly Ash and Carbon Nanotubes (CNTs). Four types of mixes such as M40 (control), M40 incorporating 40% GGBS, M40 containing 30% Fly Ash and M40 with CNTs (0.01%-0.15%) distributed using supersonication in xylene were examined. The mechanical properties such as compressive, split tensile, and flexural strength were evaluated at 3, 7, and 28 days, in addition to durability tests conducted through Rapid Chloride Penetration and Water Permeability tests. The findings indicated that CNTs notably enhanced performance, especially at concentrations ranging from 0.03–0.05%; especially, the compressive strength increases by 56%, tensile strength increases by around 20% and flexural strength enhanced by around 39% respectively as achieved for 0.03% CNTs. Furthermore, the durability of the CNTs modified concrete has also improved, achieving up to a 100% decrease in water permeability and a 34.56% reduction in chloride penetration. The study concluded that the GGBS- modified concrete outperformed Fly Ash- modified concrete, while CNTs- modified concrete provided the most significant improvements in mechanical and durability properties, showcasing their potential in sustainable concrete.