Properties of Sustainable Alkali-Activated Permeable Concretes Developed Using Agro-Industrial By-Products

The challenges of urban surface runoff and heat island effects, which arise from infrastructural development, can be effectively mitigated using macro-porous permeable concretes. By integrating the advantageous properties of alkali-activated materials, these permeable composites may attain exceptional effectiveness and environmental friendliness. This experimental research presents the development of permeable concrete composites with the use of industrial by-products, including ground granulated blast furnace slag (GGBS) and waste foundry sand (WFS), as well as agro-waste product, i.e., sugarcane bagasse ash (SBA). Alkaline activator solutions were prepared by combining the calculated amount of liquid sodium silicate with sodium hydroxide flakes. GGBS and SBA served as binders, with crushed granite as coarse aggregate and WFS as fine aggregate. The main objective of this investigation is to examine the influence of SBA, in combination with slag, on the fresh and hardened properties of alkali-activated permeable concretes. Experiments were conducted to optimize the SBA percentage based on hydraulic conductivity (i.e., permeability) and compressive strength after 28 days of air-curing. The control and optimal mixes were subjected to extended evaluations to determine tensile strength after 28 days of air-curing. The mix containing 100% GGBS and 0% SBA served as the reference mix, with the optimal 10% SBA mix used for comparative analysis to understand its consequence on the properties of permeable concretes. Results indicated acceptable mechanical performance at a mix ratio of 10% SBA to 90% GGBS as binders. This study aims to enhance understanding of the engineering behavior of alkali-activated permeable concretes, facilitating the rational design of a type of sustainable permeable concrete pavement systems through the effective use of agro-industrial waste products.