Performance Evaluation of Binary and Ternary Blended Supplementary Cementitious Material Concretes: Mechanical Strength, Durability, and Embodied Carbon Indices Under IS 456 Framework

Abstract

The escalating environmental burden of ordinary Portland cement (OPC) production contributing 0.83 kg CO₂ per kilogram of clinker [1] and representing 5–8% of global greenhouse gas emissions [2] necessitates systematic evaluation of supplementary cementitious materials (SCMs) as partial OPC replacements in structural concrete. This paper reports a comprehensive experimental investigation comparing twelve concrete mixes: OPC control (M30), binary replacements with fly ash (FA: 20%, 30%, 40%), ground granulated blast furnace slag (GGBS: 30%, 50%, 60%), silica fume (SF: 8%, 10%), and two optimised ternary blends (FA20+GGBS30 and FA30+GGBS20 at 50% total OPC replacement). All mixes are proportioned at w/b = 0.45 per IS 10262: 2019 [3] with M30 target. Compressive strength at 7, 28, 56, and 90 days, flexural strength, split tensile strength, rapid chloride permeability (RCPT per ASTM C1202 [4]), water absorption, and modulus of elasticity are evaluated. A CO₂ Saving Index (CSI) and multi-criteria sustainability ranking using Hammond and Jones ICE database coefficients [5] are applied to all mixes. The ternary blend FA20+GGBS30 achieves 28-day compressive strength of 39.2 MPa (IS 456 M35 [6] compliant), 90-day strength of 53.8 MPa, RCPT of 584 coulombs (Very Low [4]), and 36.8% embodied CO₂ saving relative to OPC control. The FA30+GGBS20 blend achieves the highest CO₂ saving (46.9%) while maintaining IS 456 [6] M30 compliance. These results confirm ternary SCM blends as technically superior and environmentally optimal for Indian structural concrete applications.