Building Materials: Personal Environments - Case Study Example

Building Materials: Personal Environments Building materials are also the stuff of our personal environments. They are all around us, and literally part of our worthy requirements. Careful selection of environmentally sustainable building materials is the easiest way for architects to begin incorporating sustainable design principles in buildings. This principle provide important guidelines for the selection of building materials. Each step of the manufacturing process, from gathering raw materials, manufacturing, distribution, and installation, to ultimate reuse or disposal, is examined for its environmental impact. A material's life cycle can be organized into three phases: Pre-Building; Building; and Post-Building. The basic ingredients for building products, whether for concrete walls or roofing membranes, are obtained by mining or harvesting natural resources. In reality, a material is only considered a renewable or sustainable resource if it can be grown at a rate that meets or exceeds the rate of human consumption. Some sustainable building materials rely on new technology, others reinvigorate centuries-old methods. The latter have a track record that makes performance easier to anticipate and evaluate. New technologies require testing over time. Advice from other architects and building owners who are using these new technologies can assist in determining their long-range effectiveness. (Sharma 18-20) Properties of common building materials are divided into Physical properties, Mechanical Properties, Thermal Properties, Electric Properties and Acoustic Properties. Physical properties includes density, melting and boiling temperature. Mechanical Properties includes basic mechanical properties, such as elastic modulus, shear modulus, Poisson's ratio, and mechanical strength properties, i.e., yielding stress, ultimate stress, elongation. Thermal Properties includes Coefficient of thermal expansion and thermal conductivity. Electric Properties includes Electric resistivity. Acoustic Properties includes Compression wave velocity, shear wave velocity and bar velocity. ASPHALT and BITUMEN Asphalt is a dark brown to black cementitious material in which the predominating constituents are bitumens that occur in nature or are obtained in petroleum processing. Asphalts are highly complex and not well-characterized materials containing saturated and unsaturated aliphatic and aromatic compounds with up to 150 carbon atoms. Their composition varies depending on the source of crude oil. Many of the compounds contain oxygen, nitrogen, sulfur, and other heteroatoms. Asphalt typically contains about 80% by weight of carbon; around 10% hydrogen; up to 6% sulfur; small amounts of oxygen and nitrogen; and trace amounts of metals such as iron, nickel, and vanadium. The molecular weights of the constituent compounds range from several hundred to many thousands. Asphalt Physical Properties are a direct result of its chemical composition.. Within a certain temperature range an asphalt is also viscoelastic, which means that it exhibits the mechanical characteristics of viscous flow and elastic deformation. Generally, asphalts are characterized by their physical properties. Softening Point: Range of temperatures that the asphalt softens using a ring and ball technique. Sometimes thought of as the melting point. Penetration How far a weighted needle or cone will sink into the asphalt during a set period of time. Viscosity An indication of how thick or thin the liquid asphalt is at various Temperatures. Flash Point Temperature that the heated asphalt will ignite. The softening point and penetration are usually the most commonly used measurements for classifying an asphalt's properties. Generally, when comparing asphalts, as the softening point increases, the viscosity also increases, the penetration drops and the flash point rises. The widespread use of asphalt relies on its remarkable waterproofing and binding properties. Asphalt is used for Buildup Roofing, Waterproofing, Damp-roofing, Rubberized Joint Sealer, Canal, Ditch, and Pond. Bitumen is a generic term for natural or manufactured black or dark-colored solid, semisolid, or viscous cementitious materials that are composed mainly of high molecular weight hydrocarbons. PLASTICS Plastic materials display properties that are unique when compared to other materials and have contributed greatly to quality of our everyday life. The word ‘Plastic’ comes from the Greek "plastikos" meaning pliant or pliable. It described any substance capable of being shaped, deformed or moulded. In modern usage, the word ‘plastic “generally defines that group of natural or synthetic materials which are capable of being formed or "moulded" into products using heat or pressure. Plastics, properly applied, will perform functions at a cost that other materials cannot match. Many natural plastics exist, such as shellac, rubber, asphalt, and cellulose; however, it is man's ability to synthetically create a broad range of materials demonstrating various useful properties that have so enhanced our lives. Plastics are greatly used in building industry. phenol formaldehyde plastic (Bakelite), even today, important engineering material used in building construction. The chemistry for nylons, urethanes, and fluorocarbon plastics were developed; the production of cellulose acetate, melamine, and styrene molding compounds began; and production of commercial equipment to perform the molding and vacuum forming processes began. Chemists continued the development of materials, such as ABS, acetals, polyvinyl fluoride, ionomers, and polycarbonate. The injection molding, thermoforming, extrusion, transfermolding, and casting processes were all improved. This allowed the industry to provide an even greater number of cost-effective products suitable for many, more demanding engineering applications. It is important for the chemist to know how long the polymer chains are in a material. Changing the length of the chains in a thermoplastic material will change its final properties and how easily it can be shaped when it is melted. Plastics are classified into ‘Thermoplastic’ and ‘Thermosetting plastic’ materials relating to their forming properties. The terms "THERMOSETTING" and "THERMOPLASTIC" have been traditionally used to describe the different types of plastic materials. A "THERMOSET" is like concrete. You only get one chance to liquify and shape it. These materials can be "cured" or polymerized using heat and pressure or as with epoxies a chemical reaction started by a chemical initiator. A "THERMOPLASTIC", in general, is like wax; that is, you can melt it and shape it several times. The "thermoplastic" materials are either crystalline or amorphous. Advances in chemistry have made the distinction between crystalline and amorphous less clear, since some materials like nylon are formulated both as a crystalline material and as an amorphous material. Some examples of the various types of plastic materials commonly used in bullding construction are PVC, Nylon, Acrylic, Polycarbonate, ABS, Phenolics, Epoxies, Melamines. Plastics products are videly used in plumbing and electrical works because of their unique advantage. PAINTS Paint consists of two things, pigment and binder. Pigment is what gives color to paint and in its raw form it is a fine powder. Binder is what holds the pigment and adheres it to a surface. The pigment particles are insoluble and merely form a suspension in the binder. There are a great many pigments in the world, from a variety of sources. Some pigments are earth pigments. Artificial inorganic pigments, on the other hand, are colors that are produced rather than found. Many of these pigments were made and discovered by the alchemists of antiquity. Natural organic pigments have sources that are either vegetable or animal, rather than earth or mineral. Finally, there are the synthetic organic pigments, which saw their birth in the nineteenth century. The chemistry of paint is a continuously developing science and although the ingredients have changed over the years, the four basic types of materials that make up paint are as follows:- Solvent - This is the liquid that carries the solid components of paint. Binder - The binder or resin is one of the most important components of paint. It is the basic solid film former that remains after the solvent has evaporated and which binds the pigment particles together into a cohesive paint film. The binder determines many of the necessary film properties such as adhesion, gloss level, hardness, abrasion resistance, flexibility, speed of drying and durability. The more specialised binders include polyurethane resins, epoxy resins, silicone based resins, acrylic resins and inorganic silicate based resins. Pigment - This is the component that gives paint its other most important properties of colour and opacity. The pigments used in paint are normally present as fine solid particles that are dispersed, but not soluble, in the binder and solvent. The most common pigment used in paint is titanium dioxide and the majority of white paints use this pigment. Other inorganic coloured pigments are used such as red and yellow iron oxides, aluminium flakes and mica flakes. Zinc is used in many anti corrosion primers. Additives - Additives are the specialist components of paint, they are used in small quantities to improve production and storage properties of the liquid paint product as well as application and other performance properties of the paint film. Some typical additives that are used are, wetting or dispersing agents, used to facilitate wetting of the pigment particles and dispersion of coarse aggregated pigment particles to the degree of fineness required. Anti-settling agents, used to reduce settling of pigment particles during storage. Anti-skinning agents, used to prevent the formation of a tough skin film on the liquid paint during storage. Drying/Curing agents, used to improve and control the drying properties of the paint film. Stabilisers, used to improve long term storage properties of the liquid paint. Anti-foaming agents, used to prevent foaming of water based paints during manufacture and during application. Anti-marring agents, these are usually silicone based compounds that are used to improve resistance to scratching and marring of the paint film. Anti-mould agents, used to reduce mould growth on the paint film in very damp and humid environments. MASTICS AND CAULKING MATERIALS Caulking materials are required to seal and permit movement under many conditions. The ability to remain in place and to provide a seal in a joint while subject to relatively large distortions is the primary characteristic of caulking material. They are often the only line of defense against the entry of water and frequently the successful performance of other building materials depends on them. Although the quantities of caulking used in buildings are comparatively small, their importance is sufficient to warrant the most careful attention with respect to joint design, material selection, use and maintenance. Development of new materials, coupled with new methods of building, has increased the importance and reliance placed on caulking compounds in preventing entry of water. It is difficult to divide caulking compounds into specific types either for particular applications or on a composition basis because of the range of properties that can be obtained from the many different materials that may be used in making them. It is basically classified into two, mastic and less elastic types of caulking, and the other the more recently developed high molecular weight elastomerics. A more meaningful distinction of the different types from the designer's point of view can be made on the basis of percentage elongation after weathering since it is this property that must be considered first in the selection of a caulking compound for a particular joint application.. For a particular application, where little or no joint movement is expected, conventional raw linseed oil putties may even be satisfactory. Polybutenes, butyl and neoprene rubber types can provide usable elongations up to 50 per cent. Where extreme joint movement must be accommodated in narrow joints it may be necessary to use the highly elastic caulkings such as those made from polysulphide polymers or silicone rubbers which can provide usable elongations of over 100 per cent after weathering. In addition to the elongation requirements mentioned there are a number of properties that must be inherent in a sealant to enable it to fulfil its function properly. It should be cohesive and adhere well to the material to which it is applied. Workability over a range of temperatures is also essential to ensure proper filling of the joint and a smooth and uniform surface. After application and exposure to the atmosphere it should form a non-tacky, tough, elastic skin over a flexible interior mass. It is essential that in aging a sealant retain its flexible properties with a minimum of shrinkage. Although linseed-oil putties are used almost exclusively for glazing wooden sash, they qualify as caulkings in the strict sense by serving as a sealant in preventing the entry of water. Putties are made by mixing thoroughly finely divided calcium carbonate and raw linseed oil. The mastic types of caulking are composed of a vehicle, a solvent, driers and mineral stabilizers. Mineral spirit solvents are used to adjust the workability of a caulking by reducing the viscosity of the vehicle, and aid greatly in the ease of application. The above materials are oxidizing types of mastics and are used in exposed areas where painting over them may be desirable. They must be used with materials having low thermal coefficients of expansion.. They are ideal as general sealants in weatherproofing around windows and doors and for sealing joints between wood and masonry. Today the world is changing rapidly. Technology and its influence has changed human’s life style. The world moves so fast, events happen so quickly in every sphere of life, that success is impossible without keeping in close touch with the latest development. So deep understanding of the selected commonly used building products will enhance its suitable application in the industry. Works cited Sharma .P, 2005, Building Materials, Kamal Publishers, New Delhi, India. Ralph Wolfe, 1975, Storey Publishing, LLC Joseph B, 1999, Applied Statics, Strength of Materials, and Building, Prentice Hall [http://pubs.acs.org/cen/coverstory/84/8442cover.html], retrieved on 28 November 2006. [http://www.astm.org/STATQA/webptppl.htm] retrieved on 28 November 2006. [http://zieglerchemical.com/asphalt.htm] retrieved on 28 November 2006. 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