Development and Performance Evaluation of Metakaolin–GGBS-Based Sustainable Grouts for Semi-Flexible Pavement Applications

Abstract

The present research aims to develop a sustainable, high-performance grout mix for semi-flexible pavement applications by partially replacing Ordinary Portland Cement (OPC) with Metakaolin (MK) and Ground Granulated Blast Furnace Slag (GGBS). The experiments were carried out in two steps: Portland cement was partially replaced with MK (10%, 20%, and 30%) to determine the optimum mix proportions for rheological and mechanical behavior. The selected optimal MK content was mixed with GGBS at 50%, 60%, and 70% replacement levels. Flowability was evaluated using flow time tests, and DIOs assessed mechanical performance through compressive, tensile, and flexural strength testing. The results showed that a 20% MK replacement level achieved a balance between workability and strength, with an optimum flow time of 14.03 s and a compressive strength of approximately 32.2 kN at 7 days of age. However, incorporating GGBS with a 20% MK blend enhanced the sustainability of these blended grouts without sacrificing their mechanical properties. The MK-GGBS grout-60% GGBS (60% GGBS) showed the highest compressive and flexural strengths, which can be considered for semi-flexible pavement applications. The incorporation of MK and GGBS reduces energy consumption during cement production, which is widely known as a significant contributor to global warming. It increases the durability of grouting materials under traffic loading.