Civil Engineering Reference
In-Depth Information
Besides the traditional application of these fabrics, randomly mixed palmyra
fibre and glass fibre hybrid composites have been proposed as an eco-friendly
composite and their mechanical properties and moisture absorption have been
studied in Velmurugan and Manikandan (
2007
). It showed that the mechanical
properties of the composites are improved due to the addition of glass fibre along
with palmyra fibre in the matrix. Addition of glass fibre with palmyra fibre in the
matrix decreases the moisture absorption of the composites. Furthermore, the
mechanisms of fibrous insulation where the fibre nanofibre technology (fibre
diameter less than 1 micrometre) have been investigated (Gibson et al.
2007
).
However, very little research has been done on this topic. It has been found that
fibres below 1 lm in diameter are not thermally efficient at low fibre volume
fractions and performance gains in existing thermal insulation materials may be
possible by incorporating a proportion of nanofibres into the structure, but large
diameter fibres would still be necessary for durability and compression recovery.
6.2 Reinforced Composites
The principal advantages of natural vegetable fibres over traditional fibres, such as
glass and carbon fibres, are their good specific strengths and modulus, low density,
economical viability and biodegradability. They have good thermal resistance.
However, due to some disadvantages that vegetable fibres possess, industry of
vegetable-fibre-reinforced composites has been substantially developed and active
for decades. Indeed, vegetable fibre composites have a long history dating back to
200 BC in China where straw-reinforced bricks were used in the wall structures of
tha Great Wall of China. Composites research has also a long history at tech-
nologies to create building products.
Composite is a microscopic or macroscopic combination of two or more dis-
tinct materials with an interface between them. Most composite materials are said
to have two phases: the reinforcing phase and the matrix phase. The reinforcing
phase can be, for example, the vegetable fibres, that are embedded in the matrix
phase. The matrix material can be, for example, ceramic or polymer. The aim is to
rectify some specific shortcomings of the materials and to improve the overall
performance. For example, concrete, cement and mortar are the most widely used
construction materials in building industry. These materials are all intrinsic brittle.
Cracks or other flaws in them will quickly propagate when they are stretched in
tension. The use of fibre reinforcement systems can help brittle materials to resist
the tensile forces. As described previously, vegetable fibres have composite like
structures which make them suitable as reinforcing materials in the composites.
Composites take advantage of the properties of vegetable fibres that they contain
cellulose, a kind of natural polymer, for reinforcing materials. The fundamental
design concept of composites is that the matrix phase accepts the load over a large
