Microstructural Analysis for Mechanical Behavior of Granular Waste Materials

Abstract

Many granular waste and recycling materials are being considered as substitutes for natural aggregates in construction applications. Incinerator bottom ash waste (IBAW), a residue from burning household waste, was previously landfilled, but now two-thirds of this ash is recycled, primarily in road construction. In this study, IBAW was mixed with limestone to produce a blend with acceptable properties for use as a road foundation layer. Cement was added to the blends to improve their mechanical characteristics. Scanning electron microscopy (SEM) was used to study the physical and chemical features of untreated and cement-treated IBAW blends and to identify the nature of the materials and any secondary reaction elements, especially after mixing with water. The micromechanical behavior of limestone–IBAW blends under uniaxial compression stresses was modeled on the basis of SEM images of the blends' microstructures. The results of micromodeling in general matched the experimental data very well. Microstructure modeling proved the high stiffness of the cement-treated blends. The material behavior in the plastic stage changed significantly with a change in the geometry and stiffness of the inclusions. Experimental and modeling results also showed that IBAW material behaved as a conventional aggregate. Results demonstrated in general that microstructural analysis was quite useful in describing the mechanical behavior of IBAW and could be applied to all granular waste materials.