Comprehensive Study on the Effect of Nano-TiO₂ as Cement Replacement and Glass Fiber as Reinforcement on Mechanical and Durability Performance of M35 Concrete

Significant advancements in concrete performance can be achieved via nano-scale cement replacement and fiber reinforcement strategies. This study examins and explore the influence of nano-titanium dioxide (TiO₂) as a partial cement substitute or partial replacement and alkali-resistant glass fibers as mechanical reinforcement. In the first phase of the study, concrete mixes were prepared with varying percentage of nano-TiO₂ contents ranging from 0.25% to 3.0% by weight of cement, in 0.25% increments. Among all the mixes, the 2.0% TiO₂ blend yielded the highest strength and durability parameters which demonstrates itssuitability for further optimization and considiration. In the second phase, the glass fibers were incorporated into the 2.0% nano-TiO₂ mix at dosages of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% respectively by volume. The optimum results were achieved at 0.6% fiber content. Comprehensive mechanical testing—including compressive, tensile, and flexural strength was conducted at 7, 14, 28, and 90 days. Durability assessment encompassed a comprehensive series of tests, including water absorption, sorptivity, rapid chloride penetration test (RCPT), and ultrasonic pulse velocity (UPV), each aimed at evaluating the concrete’s resistance to moisture ingress, ion permeability, and internal structural integrity. The results showed notable enhancements in all performance metrics for the optimized mix. Compressive strength increased by over 30% compared to control by day 90, while permeability was significantly reduced below the certified range (below 6%), indicating matrix densification. The combination of nano-TiO₂ and glass fibers proved to be synergistic, simultaneously improving microstructure and load-bearing capacity. The findings advocate for a multi-scale modification strategy in producing durable, high-performance concrete suitable for moderninfrastructure needs.