Fire-Resistant Properties of Building Materials Assignment

Fire-Resistant Properties of Building Materials - Assignment Example In addition, a recommendation will be made on the building materials best suited for the construction of a proposed building. Fires generally produce temperatures of approximately 1000C which can seriously affect the structural integrity of a building. Among the effects of fire is the loss of strength of the building material which can result in building collapse. In addition, thermal expansion associated with high temperatures may affect structures that are not directly in the vicinity of the fire. With the exception of timber, all materials used in building construction will begin to lose strength at temperatures exceeding 250C. This effect may be permanent. Metals begin to form droplets beginning at 300-350C. Concrete changes colour to pink at 250-300C. Chemical effects occur at 650C for aluminium and its alloys, and 1100-1200C for copper and iron (Prentice, 1990). Timber is one of the oldest materials used in building construction. The properties of timber are dependent on the type of wood used in construction, and how it has been treated. Wood responds well to tensional and compression forces but can bend due to the fibrous nature of this material. Wood can be a fire resistant material as it is subject to charring, which means that the wood in the centre may be protected during combustion to retain the structural integrity of the building. For the most part, however, timber is rapidly consumed by fire and can enhance the intensity of a fire since the material is subject to combustion. Timber used in building materials can be made more fire-resistant by coating the surface of the timber with fire-resistant chemicals such as ammonium phosphate and soleplate, borax and boric acid (Jones, 1986). Heavy wood timbers may be fire-resistant since the wood burns slowly inward causing charring of the exterior while the inner wood layers remain protected for significant periods of time.     Ã‚  

Wind turbines Essay Example | Topics and Well Written Essays - 2000 words

Wind turbines - Essay Example According to studies, wind contributes only less than 1% of the world's energy needs (Grose 1). Even if the percentage of contribution is very low, the use of wind turbines as means to generate electricity grow continuously. This is because people nowadays discover the good benefits of using wind turbines in terms of environmental factors. However, some disadvantages still prevent other people from using wind turbines and few of these reasons are related to high cost of manufacture and noise created by these machines (Mahoney 2). Ongoing improvements on the blade's design and material are continuously done to further develop the machine in terms of its aerodynamic properties and performance. A wind turbine is a machine that can generate electricity through the use of wind power. A wind turbine has large rotating blades that are capable of capturing wind and creating kinetic energy. This energy is converted to mechanical energy which is used to generate electricity for various purposes (Mahoney 1). Shown below are the parts of a typical wind turbine: The horizontal axis wind turbine (HAWT) is also known as the classical or most commonly used wind turbine in the world. The axis of rotation of these turbines is horizontal to the ground and parallel to the wind stream (Mathew 16). Shown is a diagram showing a sample of a horizontal axis wind turbine. .. Shown is a diagram showing a sample of a horizontal axis wind turbine. The advantages of using HAWT are its structural stability and changeable blade pitch that allows greater control of the turbine and aids the blades in catching the maximum amount of wind. Versatility is also seen as one of its advantage in terms of its ability to be feathered in case of storms (Mahoney 1). 2.2.2. Vertical Axis Wind Turbine Vertical axis wind turbine (VAWT) is different from HAWT because it is vertical to the ground and almost perpendicular to the wind direction. The VAWT can receive wind from any direction and so, complicated devices are avoided. The advantage of using VAWT is that they are not needed to be built very high. Maintenance is also easier since the VAWT is located nearer to the ground. The design is also not complicated and blades can easily be seen by birds (Mathew 19). On the other hand, VAWTs are less efficient than HAWTs since they can only produce energy that is 50% of what HAWTs can produce. Another downfall of VAWTs is that it can only rotate faster in higher elevations and with high wind velocity. Lastly, the turbine must be dismantled first in order to change or repair some parts when necessary (Mathew 19). Shown in diagram 2 is a sample of a vertical axis wind turbine. 2.3. Types of Horizontal Axis Wind Turbine Blades Wind turbine can be classified as single bladed, double bladed, and three bladed. The cheapest among the four classifications is the single bladed wind turbine since it only consumes small amount of material and labor. On the other hand this design is not ideal since balance is also an important factor in wind turbine construction and single bladed wind