Experimental Investigation on Mechanical and Durability Properties of M25 Grade Concrete

Abstract

The increasing demand for sustainable construction materials has driven extensive research into the use of industrial by-products as supplementary cementitious materials (SCMs) in concrete, offering the dual benefits of reducing Portland cement consumption — responsible for approximately 8 percent of global CO₂ emissions — and improving certain concrete properties through pozzolanic and latent hydraulic reactions. This paper presents a systematic experimental investigation of M25 grade concrete incorporating fly ash (FA) and ground granulated blast furnace slag (GGBS) as partial cement replacements at various proportions: 0% (control, M0), 15% FA (M1), 30% FA (M2), 15% GGBS (M3), and 15% FA + 15% GGBS combined (M4). All mixes were designed to IS 10262:2019 guidelines at a constant water-to-cementitious-material ratio of 0.40. Fresh properties (slump, compacting factor), mechanical properties (compressive strength at 7, 28, and 56 days; split tensile strength; flexural strength; elastic modulus), and durability properties (water absorption, sorptivity, accelerated chloride penetration, sulphate resistance, and carbonation depth) were evaluated following relevant Indian Standards. Results demonstrate that the combined FA + GGBS blend (M4) achieves the highest 28-day compressive strength (35.2 MPa, 16.6% above control), highest flexural strength (4.82 MPa), and best durability — with 56.3% lower chloride penetration depth than the control — while simultaneously reducing cement content by 30% and total material cost by 5%. The hybrid SCM approach is identified as the most beneficial formulation for both structural performance and sustainability, with application recommendations for general construction in the Western Maharashtra region.