Civil Engineering Reference
In-Depth Information
landfill as residue. Since glass is not biodegradable, landfills do not provide
an environmentally friendly solution. There is a need to develop new markets
to recycle waste glass.
Use of recycled materials in construction is among the most attractive
options because of the large quantity, low quality requirements and widespread
sites of construction. The main applications include a partial replacement
for aggregate in asphalt concrete, as fine aggregate in unbond base course,
pipe bedding, landfill gas venting systems and gravel backfill for drains
(Shi and Zheng, 2007). The use of recycled waste glass in Portland cement
and concrete has also attracted a lot of interest worldwide due to increased
disposal costs and environmental concerns. This is the background to the
development of eco-efficient concrete with recycled waste glass, i.e. recycled
glass concrete. Recently, many studies have focused on the use of waste glass
as aggregate for cement concrete or as cement replacements. This chapter
summarizes fresh properties, mechanical properties and durability of recycled
glass concrete, and the influence of recycled glass on these properties.
11.1.1 Source of waste glass
Based on the most common compositions, glass can be classified into
the following categories: vitreous silica, alkali silicates, soda-lime glass,
borosilicate glass, lead glass, barium glass and alumino-silicate glass. Small
amounts of additives are often added during the production of glass to give
glass different colours or to improve specific properties. Soda-lime glass is
most widely used to manufacture containers, float and sheets. Lead glass
is mainly for crystal tableware, TV screens and display screen equipment.
Borosilicate glass is for making glass-fibers, wool insulation, and ovenware
and thermos flasks. The alumino-silicates glass is for scientific and optical
apparatus. The typical compositions of different types for different applications
are listed in Table 11.1.
glass makes up a large component of household and industrial waste. In
waste glass, container glass accounts for approximately 80% of waste glass.
On a colour basis, 63% is clear, 25% is amber, 10% is green and 2% is blue
or other colours. The main composition of these glasses is the same except
for small amount of additives used for colour purpose. Soda-lime glass
consists of approximately 73% SiO
2
, 13-13% na
2
O and 10% CaO. Thus,
based on their chemical composition, soda-lime glasses will be pozzolanic
materials.
The second major type is lead glass, from colour TV funnel, neon tubing,
electronic parts, etc. however, a serious concern for using this type of glass
in cement and concrete is the high lead content in the glass, which can be
potentially leached into the environment. Borosilicate (Pyrex) type glass is
so expansive that under no circumstances should it be added to concrete.
