TERM PAPER ON TIMBER COURSE: CVE411 GROUP: 5 LEVEL: 400L DEPARTMENT: CIVIL ENGINEERING UNIVERSIRTY OF BENIN, EDO STATE. NIGERIA 2017/2018 SESSEION 02/04/2018 GROUP MEMBERS S/N NAMES MAT. NO DEPT 1 OKWESE GODSPOWER C. ENG1403540 CVE 2 ONWUCHEKWA OBIALOR PHILIP ENG1403543 CVE 3 ORHUE LANGFORD E. ENG1403544 CVE 4 OSEMWOTA JEFFERY E. ENG1403546 CVE 5 OSIFO O. EMMANUEL ENG1403547 CVE 6 AGHEDO GREGORY ENG1406909 CVE 7 GBOBODO OREZI DESMOND ENG1406922 CVE 8 EBIMODEI M. TOHUR ENG1406915 CVE INTRODUCTION Timber is the most useful and important material for construction in building without which entire process is incomplete. Selecting timber is not an easy task as it seems to be, because timber has different type and selecting the right material is an important key. Timber is again an expensive material to be incorporated in a building for different purpose for which it should be necessarily be strong and tough. There are many useful needs of timber during the construction of building such as in doors, windows, cupboards, cabinet and railings which contribute a lot in the beautification and overall look of interiors. Timber has many other uses but which type of timber should be used for right purpose is important to know because if timber used in construction comes out to be of low quality then one may need replacement again and again. Timber while selecting should be considered for its quality aspect which must be free from any decay like rotten, warp, knot, fungi and mold or termite so that it would not give problem afterward. Before purchasing timber material for the construction, one must be well informed regarding timber types and forms to select as a single knot can bring down the show of whole wood work. TYPES OF NIGERIA TIMBER There are many types of timbers in Nigeria but to mention a few S/N 1 2 3 4 5 Botanical Name / Scientific Name Mitragyna ciliata, stipulosa Common Nigeria NAME Y – Abura Terminalia superba Ibibio-uburu Benin Egboin-nofua, Ibibio Afara (White) White afara, Limba limbo Ofram. Terminalia ivorensis Edo-ocha Y=Afara Benin. Egboin-nebi Edoi-Oji Afara (Black) Black afara Idigbo Gossweileinidendron balsamiferum Albizia spp Y= Idigbo Benin = Agba, Achi Yor Loshi-orin Benin- Ekpaghudo Hau:- Nyie avu Yor:- Ayinreta Trade Name Other Names Elelom, Subuha Agba Albizia Okuro, pampena 6 Alstonia boonei Benin: Ukhu; Egbu Alstonia Otondo, Stoolwod 7 Antiaris Africana Yor:- Ahun Benin: Ogiovu Antiaris Ako 8 Afzelia spp Yor: Oro Benin: Arinyan Hau: Kawo Apa Bilinga, Doussie 9 Distemonanthus Yor:- Apa Benin: Anyaran Ibibio: Ochasi Ayan Ayanran, satinwood Berlinia Essoule benthamianus 10 Berlinia spp Yor: Anyan Benin: Ekpogboi Hau: Dokar rafi Ibibio: Ububa Yor: Apado etc. Properties of Timber The properties of timbers are determined by the structure of the wood, i.e., the types of cells and the chemical composition of the cell walls and cell contents, and by the proportion of the various cell types present in the wood. The distribution and arrangement of these wood elements vary considerably in different species of trees. Properties of Timbers Required for Joinery and Cabinet Work The characteristics of timber suitable for furniture making and which are important to the cabinet maker include: The Physical Characteristics 1. Colour Depends on the substances and chemicals in the cells and cell walls. Most timbers show variation in colour between species and within species. Colour descriptions usually relate to the heartwood. Finishes, light and weather all affect colour. Tasmanian Oak Radiata Pine Blackwood Jarrah 2. Grain Grain is used to describe the cells and their direction in the timber. The tree is made up of millions of tiny narrow cells. Their length generally follows the same direction as the length of the tree. Deviations in direction often occur and are therefore not always consistent grain direction within the tree. Knots or irregular growth of a tree may also distort grain direction. The grain will also be effected by the conversion method used. Quarter sawn: the edges of the growth rings are seen on the face. Back sawn: displays growth ring markings (known as cathedral grain) Types of grain Straight grain Sloping grain Interklocked grain Wavy grain 3. Figure A term applied to timbers which possess unusual or attractive designs resulting from variations in colour, grain and texture due to the natural arrangement of the elements, method of conversion or irregularities in the tree such as knots, burls and crotches. Major figures are: bird’s eye, fiddleback, ropey, ribbon, swirl, wavy and wild. Bird’s eye Fiddleback Swirl Wavy 4. Texture Texture is dependent on the size and arrangement of the wood cells. Timber can be coarse, fine, even or uneven and either rough, smooth or oily to touch. The Mechanical Properties 1. Density/Weight Density is the mass of wood substance and moisture enclosed within a piece expressed in kg per cubic metre. (Kg/m³) Heavy timbers have thick cell walls and small cell cavities; this means that it is made up of a lot of wood substance and little air. Whereas light timbers have thin cell walls and large cavities, these have little wood and a lot of air. Balsa is an excellent example of light timber as only 7% of its volume is solid wood, the remaining is air cavities. 2. Strength Strength refers to a timbers ability to resist and withstand the different types of external forces. This property is due to the (abundance) of interlocked fibres to provide strength. The direction and structure of the cells also effects the strength of the timber, straight grained timber is stronger than a cross grained or wavy timber. Defects like cracks, decay or a knot will decrease the strength of the timber. The strength of a timber is important when designing furniture where the member will be placed under stress, such as bed rails, table rails and chair construction. 3. Durability of Timber • Durability is being able to withstand disease or insect attack. • Impregnated in the cell walls during growth are chemical substances, oils, resins that cause the timber to be durable. • Impregnating the wood with a suitable preservative can increase durability. 4. Hardness The ability to resist indentation, bruising and abrasion This can be gauged in different ways: The timbers resistance to nails, the difficulty in sawing and working, and the resistance to wear. As a rule, hardwoods are more resistant to wear than softwoods as they have small thick walled cells, and the softwoods generally have thin walled cells. The thickness of the cell wall and the smallness of the cell cavities make the wood hard. The moisture content of the wood and the maturity of the timber also affect the hardness. The Janka hardness test measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an 11.28mm (.444 in) steel ball into wood to half the ball's diameter. This method leaves an indentation. A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring. 5. Weathering The word 'weathering' is the general term used to define the slow change of materials exposed to the weather. For timber, the weathering is the breakdown of the exposed surfaces due to action of sunlight, rain, wind, dew and frost and airborne pollution. Weathering is a process distinct from decay (also called rot) which is caused by fungi. Weathering initially means that dark colours become paler through leaching and bleaching and pale colours darken because of oxidation. Eventually all exposed timber surfaces become grey. The surface may appear dirty or blotchy in situations favouring fungal organisms, but in dry or coastal climates an attractive silvery grey usually results. To prevent the weathering effects, timber requires coating with paint or oil stains. 6. Working Qualities The working qualities of timber is the ease or difficulty of sawing, planning, chiseling, carving, shaping, turning, gluing and nailing. Also the ability of the timber to take finishes such as paints, stains, fillers, polishes etc. These are influenced by the density, texture, grain, hardness and toughness of the wood. GRADING Grading is simply sorting a production run into groups that have similar properties. The grouping of the properties can be any mixture of appearance and structural properties. In order to give some uniformity across the industry there are standards for the sorting of timber products TIMBER CLASSIFICATION The terms timber and wood are often used synonymously, but they have distinct meanings in the building industry. Wood is the hard, fibrous material that makes up the tree under the bark, whereas timber may be defined as a wood which retains its natural physical structure and chemical composition and is suitable for various engineering works. Following is the classification of timber as per IS: 6534. TIMBER CLASSIFICATION ON THE BASIS OF GRADING All grading specifications are clearly distinguished between structural or stress grading, and commercial or utility grading based on Indian Standard classification. STRUCTURAL GRADING It is also known as stress grading. However, there is a small distinction between the two. Structural grading refers to the principle by which the material is graded on the basis of visible defects which have known effects on the strength properties of the material. Stress grading refers to the principle by which the material is graded by consideration of maximum principle stresses to which it can be subjected. Structural grading is further divided as: 1. Grading based on known effects of defects and estimating accumulative value. 2. Machine grading. COMMERCIAL GRADING It is also known as yard grading or utility grading refers to the principle by which the material is graded by consideration of usefulness of the material and price factors. Commercial grading is further divided in the following classes: Grade A: It is based purely, and sometimes arbitrarily, on dimensions and general appearance. The dimensions of lengths and girths for logs, or lengths, widths and thicknesses of converted material are measured according to specified methods. This system is prevalent in Kerala and Mysore. Under these classifications, teak is placed in four grades with two sub-classes in each grade. In the case of other hardwoods, there are similarly four grades in Mysore (Coorg) but the dimensions are fixed separately for each of the species. In Kerala, there seem to be only two grades of hardwoods Grade B: It is based on the best ultimate use of logs or converted material. Such a system is mostly prevalent in Andhra Pradesh and some parts of Tamil Nadu, and seems to be one of the quickest systems of grading and marking. The logs are classified into grades on the best use possible as for beams, planks, scantlings, etc., and each grade is further divided into ‘A’, ‘B’ and ‘C’ classes to indicate occurrence of defects. Only two lengths are recognized; ‘long (that is, 5 m and above) and ‘short’ (that is, under 5 m). Each log is thus quickly stamped with the first letter of the grade classification, the sub-class, and ‘L’ or ‘S’ for ‘long’ and ‘short’, for example, BAL and PBS indicate, respectively, ‘ beam, A-class, long ’ and ‘planks, Bclass, short’. Sometimes another letter is also added to indicate the species, for example, ‘T’ for teak. Grade C: This classification is based on qualitative evaluation of defects and rough estimate of out-turn of utilizable material. It is prevalent in Madhya Pradesh. Grade D: It is based purely on evaluation of ‘units of defects’ and fixing the -number of units permissible for a standard volume in each grade. Such practices are common in the Bombay region; sometimes an estimated outturn is also indicated in each grade. In general three grades are distinguished for various categories of logs and sawn timber. Sizes and other dimensions are also fixed in a few cases, separately for different species and different depots in the same state. This system is being increasingly adopted in the specifications of Indian Standards Institution, and in international grading specifications. This system has a distinct advantage of evaluating cumulative effect of defects in a particular grade. REFERENCE IS – 6534 – 1971 http://www.iiste.org/conference/upcoming-conferences-call-for-paper/ www.aboutcivilblog.com