Identification of design parameters influencing manufacture and properties of cold-bonded pond ash aggregate

This paper explores the feasibility and the process of converting of pond ashes – a waste material into artificial aggregates – a value added product. As a first step, identification of the parameters influencing manufacture and properties of artificial aggregate with pond ash has been carried out. Pond ash of both bituminous and lignite type have been chosen to make aggregate through pelletization and cold-bonding. The parameters identified are moisture content, binder dosage, pelletization enhancer and strength enhancer dosage. The range of parameters are varied and the designed experimental runs are carried out by adopting statistical technique known as central composite design of Response Surface Methodology. The physical properties of aggregate like bulk density, water absorption and open porosity and the strength property of aggregate represented through 10% fines value have been determined for the influence of parameters thus identified. Microstructure and phase composition of aggregate are represented by SEM and XRD respectively. Ordinary Portland cement, locally available hydrated lime, and hardening admixture are used as binders at varying amounts from 10% to 20% by weight. Calcium hydroxide and sodium sulphate are used as pelletization and strength enhancing admixture respectively. It is observed that the dosage of binder, strength and pelletization enhancing admixture improved the properties of aggregate. The results indicated, potentially exposes a new avenue to convert pond ash – a waste material into a value added product.