Enhancing Mechanical and Durability Properties of Concrete Through Partial Replacement of Cement With GGBS and Metakaolin

Abstract

The effort toward the use of sustainable supplementary cementitious materials such as GGBS and MK has gained momentum on account of increasing apprehension with regard to energy consumption and carbon dioxide emission [1]. In this study, a total number of five concrete mixes were prepared-one control mix was prepared with 100% ordinary Portland cement, and four blended mixes were prepared with a constant 30% GGBS and MK replacement levels of 5%, 7.5%, 10%, and 12.5% [2]. The mixes were prepared for M40 grade concrete according to IS 10262:2019, maintaining a fixed W/B ratio of 0.42. The mechanical strength and durability properties of the concrete specimens were monitored after 7, 28, and 56 days of curing under aggressive environments with H₂SO₄, Na₂SO₄, and MgCl₂ [3], [4]. Results indicated that the concretes produced using GGBS and MK in combination imparted the best performance. The high pozzolanic reactivity of MK accelerates strength gain at the early age, whereas the latent hydraulic nature of GGBS tends to increase strength continuously at later ages by improving ITZ [5]. These two mineral admixtures have interactively performed since the maximum compressive, split tensile, and flexural strengths were achieved within the range of 7.5% and 10% MK replacement. Such synergy enhances resistance against chemical attack through the formation of a denser and more homogeneous microstructure [6]. However, increasing the MK content up to 12.5% leads to a slightly deteriorated performance, which is caused by the surface area-induced increase in water consumption and loss of workability [7]. According to the experiment results, concrete containing 30% GGBS and 7.5% to 10% MK provided the best possible balance among durability, mechanical strength, and environmental sustainability [8]. This blend is hence an excellent formulation for high-performance green concrete applications.