|Classification & methods of cutting timber||Properties of wood|
|Wood a material of plant origin characterised by a hard fibrous structure and composed mainly of cellulose, hemicellulose, and lignin. The high content (22-29%) of lignin contributes unique... [Read More]
Methods of sawing
1. Ordinary sawing
2. Rift sawing
3. Quarter sawing
4. Tangential sawing
|Wood is the oldest material used by humans for construction, after stone. Despite its complex
chemical nature, wood has excellent properties which... [Read More]
Properties of wood
1. Specific Gravity
2. Moisture content
3. Thermal properties
4. Strong & light weight
|Seasoning of wood||Decay & Preservation|
Seasoning is the controlled process of reducing the moisture content of the timber so that it is suitable for the environment and intended use. Removal of the moisture from wet or green wood, in other words... [Read More]
|The traditional building materials for bridges are stones, timber and steel, and more recently reinforced and pre-stressed concrete. For special elements aluminum and its alloys and some types of plastics are used. These materials have different qualities of strength, workability, durability and resistance against corrosion. They differ also in their structure, texture and color or in the possibilities of surface treatment with differing texture... [Read More]|
|Wood as construction material||Uses and applications of wood|
|Wood is a simple engineering material, but the conception, design, and
construction process is complex with problems and places to err. In using wood in its many forms and
with its unique inherent characteristics, there are problem areas which seem to... [Read More]
1. Problems in wood construction
2. Wood defects
In concrete a substance other than active and inert matter, added in small amounts to the mix to alter its natural properties to required properties... [Read More]
Wood & Timber
Trees have age, just like humans do. Older trees are more stable but not as strong as middle-aged trees. Younger trees move more and are not ready to use. Tight grain is what we prefer, but the grain can be too tight because it will start to lose strength at some point.
As trees grow in one season, they grow faster from spring through summer and more slowly from fall through winter. That is what we see in tree rings. Tighter grain means less space in fast-growing fibre. This space in looser grain is where the moisture stays, which is why tighter grain is more stable than looser grain. Density is also heavier in tighter grain. The increased density means that the wood is stronger.
British Columbia's forest resources are managed. Forestry management controls when trees are planted and harvested. Trees that come out of these managed forests are about 50 years old, and the size of the butt (bottom) is about 14 inches. This means that the trees contain 50 rings in seven inches, or seven rings per inch. The wood we are sourcing has 8 to 13 rings per inch, so it is around 100 years old or older.
Deterioration occurs mainly due to
- Decay or rot
- Insects, marine borers
Timber not properly seasoned or subjected to intermittent wetting decays ►due to fungi, termites as various portions of the wood are used as food. They require both oxygen and excess moisture ►hence timber having less than 25% moisture or fully submerged in water will not decay or rot. Termites also attack wood. They eat wood and form tunnels or tubes inside. Certain species of beetles and ants will damage timber by digging tunnels through it using the wood for living quarters rather than food. The major disadvantage of timber is the ease with which it burns as compared with structural materials.