Optimization of GGBS as a Partial Replacement of Cement for Enhanced Strength and Durability of Sustainable Concrete

Concrete is one of the most common building materials in the world. It has great compressive strength, but it is not very durable or sustainable because it relies on ordinary Portland cement (OPC). Ground Granulated Blast Furnace Slag (GGBS), a by-product of the steel industry, was used as a partial replacement for Ordinary Portland Cement (OPC) to improve the mechanical and durability performance of concrete. The mass proportions for replacing cement with GGBS in concrete mixes were 0%, 10%, 20%, 30%, and 40%. The mix ratio was 1:1.5:3, and the water-to-cement ratio was 0.45. Mechanical performance was tested by measuring the compressive strength, split tensile strength, flexural strength, and surface hardness (using the rebound hammer test). For durability performance carbonation depth and water permeability tests were conducted. According to the findings, GGBS produced the highest compressive, tensile, and flexural strengths when 20% of OPC was substituted. It also improved surface hardness and decreased permeability, indicating increased durability. Mechanical strength, resistance to carbonation, and permeability all decreased above this point. The results validate the viability of employing GGBS as a sustainable binder, which lowers CO2 emissions and cement consumption in environmentally friendly building.