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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.

Incinerator bottom ash (IBA) is a residue from burning household waste that once was put into landfills. Nearly two-thirds of this ash is reused, primarily in road construction. In this study, IBA was mixed with limestone to produce a blend with acceptable properties for use as a road foundation layer. In situ simulative testing with a light falling weight deflectometer (LFWD) and subsequent interpretation of the surface deflection data have enabled evaluation of the mechanical properties of the foundation and subgrade layers. An experimental and modeling study of the elastic dynamic response of a foundation layer of IBA waste and limestone that was subjected to LFWD impact loading is presented. Several parameters—such as IBA content, water content, and curing time—were studied. Regression, mathematical, and three-dimensional finite element models were developed to backcalculate the LFWD moduli of the foundation layers. The modeling approach accounted for the static and impact nature of the LFWD load. Results showed that IBA blends underwent less deflection, as a foundation layer, than the control limestone blend. Backcalculated modulus results based on the dynamic effect of the LFWD load produced different values from those calculated by Boussinesq's equation, which is adopted by the LFWD manufacturer.

The use of waste and recycled materials in different construction applications is a widespread approach. In this work, incinerator bottom ash (IBA) waste was mixed with limestone at different levels, namely, 0%, 30%, 50%, and 80%, to produce blends for use as pavement foundation layers. The study focused on evaluating the resistance to permanent deformation of IBA–limestone blends, which is vital to prevent or minimize pavement rutting. An experimental program was undertaken to investigate the influence of plant-based enzyme treatment on the behavior of these blends. Cyclic and static triaxial compression tests were adopted to determine the materials’ mechanical characteristics. Emphasis was on examining the effect of various parameters, such as IBA content, enzyme content, moisture content, curing time, stress level, and number of load applications, on the behavior of the investigated blends. The accumulated permanent strain and strain rate were used to describe the blends’ shakedown stress limits. Results showed that IBA blends gave a favorable performance as foundation layers in comparison with the control limestone blend. Enzyme addition improved the permanent deformation resistance for the control limestone blend; however, it did not have any noticeable effect on the IBA blends. According to the shakedown concept analysis, all blends, at a cyclic stress level of more than 21% of the static failure stress, underwent excessive plastic strain.