Industrials by products which are able to be used as
the sources for artificial lightweight aggregate production are shown in Figure
2.5. According to Kraus (2003), recovered glass can also be manufactured as
feedstock. Various methods used for producing artificial aggregates from these
products and the properties of the aggregates manufactured are also discussed. There
are processes which include grinding, shaping and firing for the manufactures
of artificial aggregate:

·        
Coal wash waste
and flotation residues from coal processing, as well as with the addition of
red mud (Schickle, 2009).

·        
Ash from
combustion processes (Boljanac, 2007).

·        
Fine particle
waste from pumice processing (Knopf, 2000).

·        
Uncontaminated
or contaminated sediments and sludge from rivers, lakes, and water reservoirs,
as well as sewage sludge (How Ji Chen, 2012).

2.5.1    Major
Solid Wastes and Potential Use as Construction Materials

Due to the rapid growth of the development and
urbanisation, there are huge quantity of wastes generated by variety of
activities such as mining, domestic, agricultural and industrials. There is 12
billion tonnes of solid waste generated for year 2002 globally and among the
amount, 11 billion are the industrial wastes (Pappu et al, 2007).  Furthermore, for the year 2025, it is
estimated 19 billion tonnes of solid wastes generated (Yoshizawa et al., 2004).

While for Malaysia, the major solid wastes contributed
from industrial, municipal and mining and also agricultural which expected
15000 tonnes generated daily. As the result, these cause the major problem for
the environmental. Therefore, the comcept of modification of these wastes into
the building construction materials is essential. The utilization of the
industrial wastes are success being researched by researchers.There are many
years for study on the reused the solid wastes as construction materials is
succeeded practices. (Cyr et al., 2004).