Fibres for strengthening of timber structures

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 this 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, hemp and wood are on the contrary, recyclable and CO2 neutral. Their low density and high specific mechanical properties provide great advantages for timber construction. This technical report is the state of the art review of timber reinforced FRP (Fibre reinforced polymer) with a large description of the actual research projects in that field, but also of natural fibre reinforced composite. Geographic origins of the fibre, chemical constitution, mechanical properties and treatments are covered.Godkänd; 2006; 20070201 (ysko