Woods, Plastics, and Composites PDF

WOODS, PLASTICS AND COMPOSITES  Main p o i n t s covered Identify the different types of wood materials used in construction Identify the different construction materials using paper products Determine the plastic properties of materials...

WOODS, PLASTICS AND COMPOSITES  Main p o i n t s covered Identify the different types of wood materials used in construction Identify the different construction materials using paper products Determine the plastic properties of materials used in construction Identify the different method of testing woods, plastics and composite materials DIFFERENT TYPES OF WOOD MATERIALS USED IN CONSTRUCTIONS  has been used as a b u i l d i n g material for thousands of years, bei ng second only to stone in terms of its rich and storied history in the world of WOOD constructi on. human beings have successfully harnessed the u n i q u e characteristics of wood to bui l d a seemingly unlimited variety of structures. c o m m o n l y used to bui l d houses, shelters and boats, but it is also extensively used in the furniture and home d e c o r i n d u s t r y as well. Advantages Disadvantages Renewable Flammable Durable Can decay or rot due to Readily available moisture and insects High Strength to weight ratio Susceptible to volumetric Good insulating properties instability Easily shaped, repaired and Variation in strength altered within the cross section Resistance to oxidation of a tree log. Resistance to corrosive agents Non-homogeneous Shock resistance Non-uniform T i m b e r as a structural material Beams and girders Columns Railway foundation Trusses LU M B E R OR T I M B E R? Lumber Pieces of wood that are smaller than 5 inches wide by 5 inches thick ( regardless of length ). These pieces are machine - planed and sawn to fit certain dimensional and are primarily used in residential construction LU M B E R OR T I M B E R? Tim b er Pieces of wood over 5 inces wide by 5 inches thick (regardless of length ) , pieces arelarger in dimension. They are often used to construct the frames of large structures such as buildings and bridges Types of wood Wood has traditionally been classified into two primary categories: Hardwood (any leaf - bearing tree) examples: alder, balsa, beech, hickory, mahogany, maple, oak, teak, walnut Softwood ( anycone - bearing tree) examples:cedar, douglas fir,juniper, pine, redwood, spruce, yew  DEFINITION Comes from angiosperm treesthat Comes from gymnosperm trees are not monocots.; trees are which usually have needles and usually broad-leaved. Has vessel cones. Medullary rays and element that transport water tracheids transport water and throuhout the wood; under a produce sap. When viewed under microscope, these elements a microscope, softwoods have no appear aspores. visible pores becauseof tracheids H A R D W O OD SOFTWOO D  U S ES About 80% of all timber comes from softwood. Softwoods have a Hardwoods are more likely to be wide range of applications and are found in high quality furniture, found in building components decks, flooring and construction (eg., windows, doors ) , furniture, that needs to last. medium - density fiberboard (MDF), paper, Christmas trees, and much more. H A R D W O OD SOFTWOO D  HYGROSCOPIC PROPERTIES OF W O O D Hygroscopicity is the property of wood to attract moisture from surrounding atmosphere and to hold it in the form of liquid water or vapor. Water gets into wood in three ways: As a fluid through the cell lumens through capillary action As a vapor through the cell lumens As molecular diffusion through the cell walls Moisture Content of Wo o d means the relationship between the mass of water in it and the mass of the timber without the water. the moisture content of newly sawn wood is usually 40 - 200 %. Moisture Content of Wo o d in normal use the moisture content of wood varies between 8 % and 25 % by weight, depending on the relative humidity of the air. Equilibrium Moisture Content of Wood is a state corresponding to the air temperature and relative moisture, in which the moisture content of the wood remains steady. Equilibrium Moisture Content of Wood Wood ’ s ability to absorb and release moisture ( moisture capacity ) can be used as a structural benefit. PA PER A N D PU L P PRODUCTS IN CONSTRUCTION  is a thin material p r o d u c e d by pressing together moist fibers of cellulose pulp derived from wood, rags, or grasses, and drying them into PAPER flexible sheets. is a versatile material with many uses, i n c l u d i n g writing, printing, packaging, cleaning, d ecorating, and a number of industrial and c o n s t r u c ti o n processes. Newspaper Wood This design comes from Norway, where over 1m tons of paper and cardboard are recycled every year. The wood is created by rolling up paper and solvent-free glue The wood can then be sealed so it's waterproof and flame- retardant, and used to build anything you would normally build with wood. BetR-blok is a brick made from paper and other cellulose - based products. isolates much better than conventional building materials and consumes less energy. the blocks are termite, fire and mould - resistant and reduce the need for incorporating fibreglass into buildings. also produces ‘ papercrete ’ , which is asustainable concrete - like material constructed from paper pulp. Drywall is a modern building material that comes in large panels ( typically 4' by 8 ') having a gypsum core sandwiched between two heavy paper faces. These paper faces are often made from recycled paper. One face is smooth and is the surfacing face, and the other is more of a kraft paper backing face. Shoji Japanese Shōji in Japanese architecture, sliding outer partition doors and windows made of a latticework wooden frame and covered with a tough, translucent white paper. When closed, they softly diffuse light throughout the house. Fusuma In Japanese architecture, fusuma ( Japanese: 㾆 ) are vertical rectangular panels which can slide from side to side to redefine spaces within a room, or act as doors.  is a soft, wet mass of the material which is made by mixing water or PULP l iquid chemicals. is the most efficient material for paper making process as it helps to get fiber t h r o u g h the large waste material.  PRO PE RTI E S O F P L A S T I C M A T E R IA L S P L A S T IC The name Plastic is derived from the Greek word plastikos, which means able to be shaped. Available in many colors and in transparent form, plastics can be rubbery or rigid. Plastic shapes include sheet, rod, hex, pipe, cubes, balls, and tubes. P L A S T IC Plastics are generally low cost, easy to manufacture, durable, strong for their weight, electrically and thermally insulative, and resistant to shock, corrosion, chemicals, and water. Properties of Plastics as a Construction Material 1. Appearance of Plastics suitable pigments are added in the process of manufacturing of plastic material to get these different properties. So, these will give good appearance to the structure and makes it attractive. 2. C h em ic a l Re s is t a n c e o f Pla s tic s Plastics offer great resistance against chemicals and solvents. Chemical composition of plastics during manufacturing will decide the degree of chemical resistance. So, corrosive metals are replaced by plastic in the case of water carrying pipes 3. Dimensional Stability Thermo-plastic types of plastics can be easily reshaped and reused. Thermo-setting type plastics cannot be reshaped or remold once shaped. 4. Ductility of Plastics Ductile nature of plastic is very low. When tensile stress are acting on plastic member they may fail without any prior indication. Can form in any shapes. 5. Durability of Plastics Plastics with sufficient surface hardness are having good durability. Sometimes, plastics may be affected by termites and rodents especially in the case of thermo - p lastic types, however it is not a serious problem because of no nutrition values in plastic. 7. Finishing Any type of finishing treatment van be given to the plastics. Mass production of plastic particles with uniformity of surface finish is done by having technical control during manufacturing. 8. Fi r e Re s i s t a n c e The resistance to temperature or fire for varieties of plastics considerably varies depending upon the structure. Plastics made of cellulose acetate are burnt slowly. PVC made plastics do not catch fire easily. 9. Fixing Fixing of plastic materials is so easy. We can bolt, drill or glued to fix plastic material position. 10. H u m i d i t y The plastics made up of cellulosic materials are affected by the presence of moisture. The plastics made of poly vinyl chloride (PVC pipes ) offers great resistance against moisture. 11. Mai n t en an ce Maintaining of plastics are so simple. Because they do not need any surface finishing coats or paints etc. 12. Melting Point Generally plastics have very low melting point. Some plastics may melt at just 50oC. So, they cannot be used in the positions of high temperature. 1 3. Optical Property Some plastics are transparent which allows light in its original direction and some are translucent nothing but semi transparent which - allows light but changes light rays direction. 14. Recycling of Plastics We can use plastic waste disposal conveniently to produce drainage pipes, fencing, hand rails, carpets, benches etc. 1 5. S o u n d Absorption By the saturation of phenolic resins we can produce acoustic boards. These acoustic boards are sound absorbents and provide sound insulation. 16. Strength Plastic is strong material but ideal section of plastic which is useful for structural component is not designed yet. If the strength to weight ratio of plastic is same as metals, then also we cannot give preference to plastics. 1 7. Thermal Property The thermal conductivity of plastics is very low and is similar to wood. So, foamed and expanded plastics are used as thermal insulators. 1 8. We a t h er Res is ta nc e Most of the plastics except some limited varieties are capable of resistance against weathering. When the plastics are exposed to sunlight, they are seriously affected by ultra violet rays and gets brittle. 19. Weight of Plastics The Plastics have low specific gravity generally ranges from 1.3 to 1.4. So they are light in weight and easily transportable to any place in a large quantity. ME THO D S O F TE S TING WO O D S , P LA S T IC S A ND C O MP O S IT E M A T E R IA L W O O DS A S T M D 1 9 8 (for structural m e m b e r s ) determines the flexure, compression, tension, torsion and shear modulus of wood. ASTM D143 ( for small specimen ) Flexure covers the determination of the flexural properties of structural beams made of solid or laminated wood, or of composite constructions Material of specimen: consist solid wood, laminated wood, or a composite construction of wood or of wood combined with plastics or metals Compression ( parallel to grain ) This test method covers the determination of the compressive properties of elements taken from structural members made of solid or laminated wood, or of composite constructions when such an element has a slenderness ratio ( length to least radius of gyration ) of less than 17 greater than nominal 2 by 2-in. ( 38 by 38 - mm ) cross section Tension ( parallel to grain ) covers the determination of the tensile properties of structural elements made primarily of lumber equal to and greater than nominal 1 in. ( 19 mm ) thick To r s i o n This test method covers the determination of the torsional properties Shear M o d u l u s determination of the modulus of rigidity (G) or shear modulus of structural beams made of solid or laminated wood P L A S T IC S ASTM D638 ( Tensile Strength ) one of the most common plastic strength specifications and covers the tensile properties of unreinforced and reinforced plastics it used a “ dogbone ” shaped specimen-size:14mm in thickness ASTM D70 ( Flexural Strength ) The test uses a universal testing machine and a three point bend fixture to bend plastic test bars O T H E R TESTS: Compression: ASTM D 695M ( rigid plastics ) Puncture: ASTM F 1306 Co m p o si t e materials ASTM D3039 ( Tensile Strength ) determines the in plane - tensile properties of polymer matrix composite materials reinforced by high - modulus fibers