Guide To Learn
Aluminium is extracted from bauxite in two stages: 9.1.1 Purification of the ore to produce alumina (Al2O3) The first process is called Bayer process, in which the alumina in the bauxite is dissolved in a solution of caustic soda, filtered and reprecipitated to obtain aluminium hydroxide and calcinated to form pure Al2O3. 9.1.2 Reduction of […]
Steel can be used for various purposes in building works. 8.2 STEEL AS A REINFORCEMENT IN CONCRETE Although plain concrete is very strong in compression, it is very weak in tensile strength. So, steel is being used in concrete as a reinforcement as it is equally strong in compression and tension. The steel for reinforcing […]
There exist today a wide variety of wood polymer composite boards that are commonly called particle boards. Basically, these materials are made from non-chemically processed dry wood particles of various shapes and sizes and either synthethic or adhesive material. The basic materials from which particle boards are made can be broken down into four basic […]
A veneer is defined as an essentially thin sheet of wood. The thickness of veneers varies from 0.4 to 6 mm or more. They are obtained by rotating a log of wood against a sharp knife of rotary cutter or saw. The veneers after being removed are dried in kilns to remove the moisture. Another […]
Plywood is a specially processed type of wood, which consists of essentially an odd number of plies (or thin sheets called veneers) glued together in such a manner that the grain of adjacent layers is perpendicular to each other. The placing of plies normal to each other increases the longitudinal and transverse strength of plywood. […]
Wood from freshly felled trees cannot be used in construction because it contains more moisture and is undesirable in many accounts. The water is to be removed before the timber can be used for any engineering purpose. This process of drying out the timber is known as seasoning of timber and the moisture should be […]
The following are the qualities of a good timber:
From the visibility aspect, the structure can be divided into two categories: 7.2.1 Macrostructure The structure of wood visible to the eye or at a small magnification is called a macrostructure. The following are the different components (Figure 7.1). Figure 7.1 Cross section of an exogenous tree 7.2.2 Microstructure The structure of the wood […]
Trees are classified into two types, namely, 7.1.1 Endogenous In the endogenous trees, a plant grows by the addition of new cells only at the tip or end, i.e., the trees grow inwards and fibrous mass is seen in their longitudinal section. Such trees show very little branches. The timber from these trees has very […]