This
paper discusses
strengthening of glued-laminated timber in tension
perpendicular to the grain. Wood properties
are often inappropriate for high
performance structural applications. Major drawbacks like durability and high
variability can be reduced by using glued-laminated timber. A further step to
decrease the variability is to strengthen the cross-section to prevent tensile
failure
perpendicular to the grain. This has been widely investigated during
the last decades by bonding fibre reinforced polymer (carbon, aramid and glass
fibres) to timber or glulam beams, with mostly promising results. However, a
great concern about environmental friendly materials showed up a few years ago.
Mineral and petrol-based fibres are difficult to recycle and increase the
amount of carbon dioxide in the atmosphere leading, for instance, to the
preoccupant greenhouse effect. Natural fibres such as flax are on the contrary,
recyclable and CO2 neutral.
Their low density and high specific mechanical properties provide great
advantages for timber construction. Specimens of glued-laminated timber with a
volume of 0.01 m3 have
been reinforced with fibre reinforced polymer (FRP) composites, and tested in
tension perpendicular to the grain. Unidirectional laminates have been prepared
with flax and glass fibres. Epoxy resin, which provides good bonding with
hydroxyl groups in natural fibres, has been used. The results show that there
is a potential in using natural fibres for
strengthening timber structures.