Title:
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Treatment and re-utilization of incinerator bottom ash waste
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Pollution and waste are continually generated. The production of waste. however. has
increased rapidly in recent years. An efficient and safe means of either neutralizing or
disposing of this waste has been increasingly researched. In recent times, the potential
of recycling and reusing the waste in construction works has been investigated. The
studies have highlighted the benefits of such applications. In line with these studies,
the current study investigated the suitability of using Incinerator Bottom Ash Waste
(lBA W) as an alternative to conventional aggregates in the construction of road
foundations. IBA W is a residual material produced by incinerating Municipal Solid
Waste (MSW). The potential advantage of this approach is that the reuse of IBA W
helps to conserve the supplies of conventional aggregates and reduces the landfills
needed to store the waste. However, such applications may cause serious
environmental impacts as IBA W may be exposed to intermittent infiltration as a
consequence of precipitation events or altering of the water table, resulting in a
potential release of pollutants to soil and groundwater.
This work is divided into three main parts. The first part investigates the potential
environmental impacts by using leaching tests for treated and untreated IBA W. The
treatment including stabilization and chemical processes was applied in this study for
IBA W by using different types of novel and traditional additives. This treatment
aimed at immobilizing the pollutants by integrating them in a strong matrix. The
Iysimeter as a leaching tool was adopted to assess the potential impact of changing
conditions such as liquid to solid ratio (LIS), pH value, IBA W content and different
treatment agents on long-term release of heavy metals and salts to estimate the
environmental risks of IBA W. Appropriate and reliable leaching models based on
initial measurement of intrinsic material properties and simplified testing were used to
predict the release of constituents of concern from IBA W and its migration and fate
into soil.
The second part of the thesis aims at analyzing the microstructure of IBA W material
by using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray
Spectroscopy (EDXS) techniques. These tests are adopted to manifest the physical
and chemical features of IBA Wand identify the nature of the materials and any
secondary reaction elements, especially after mixing with water, with and without
additives. This helps understanding the behaviour of the materials because there is a
good correlation between the microstructural and chemical composition of the
materials and their mechanical behaviour.
The third part studies the mechanical properties of IBA W as an aggregate. An
experimental programme has been undertaken to investigate the influence of
treatment on the behaviour of IBA W blends for use as foundation layers. The research
has focused on determining the blends' resilient modulus and permanent deformation.
Cyclic and static triaxial compression tests were adopted to determine the materials'
mechanical characteristics. Light Weight Falling Deflectometer (L WFD) test was also
adopted as an in-situ evaluation for the elastic modulus of IBA W. Emphasis has been
on examining the effect of various parameters, such as IBA W content, type and
content of additives, moisture content, curing time and maximum nominal particle
size on the behaviour of the investigated blends. The shakedown concept was adopted
to evaluate the behaviour of the IBAW material under cyclic loading as a granular
material. A new calculation model was proposed to estimate the plastic deformation
of IBA W and granular materials under monotonic loading. Finite element modelling
was adopted to simulate the IBA W material behaviour under static, cyclic and impact
loading in macro and micro scales.
The main findings of this study are that IBA W can be reused safely and successfully
as an aggregate in construction applications. It also illustrated that IBA W may show
similar or even better behaviour than conventional aggregate as observed under some
conditions. IBA W also showed typical behaviour of conventional aggregates using
the theoretical and modelling approaches. Some novel and traditional treatment agents
resulted in a good improvement in IBA W behaviour in terms of environmental and
mechanical properties.
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