Building materials

BUILDING MATERIALS CONCRETE, PLASTIC & TIMBER Presented by: Mr. B. Elliott MSBTC2011

CEMENT PROCESS OF MANUFACTURING PORTLAND CEMENT Portland cement is produced from limestone. To be effective, it must have the proper amounts of four ingredients: Alumina (Al 2 O 3 ) , Iron Oxide (Fe 2 O 3 ), Lime (CaO) , and Silica (SiO 2 ) .

To produce a portland cement, limestone is first dug from a quarry. It is then crushed and ground to a powder. Once ground, the other additives may be mixed with the product in proper proportion. It is then heated to about 2900° F, driving off all remaining water. Calcium sulfate is then added to the mix once it is cooled rapidly to prevent it from re-absorbing moisture.

The calcium sulfate (CaSO 4 ) is added to control the rate at which the cement will set up. Without it, the cement would set up too fast to be of use. This product is then sifted and packaged into one-cubic-foot bags.

TYPES OF AGGREGATES sand, crushed stone, Gravel Limestone/marl River stone Shale Aggregates are classified according to roundness and size.

AGGREGATES Fine aggregates are those which will pass through a standard 5mm sieve and coarse aggregates are those which are retained on a standard 5mm sieve. The aggregates must be free from clay, mud, silt and other materials that might weaken the mix

CHARACTERISTICS OF AGGREGATES Clean Sound Well-graded Angular shaped Strong

DEFINITION OF THE TERM ‘PROPORTIONING’ AS IT RELATES TO CONCRETE This is a method of measuring the ingredients of a concrete mix to maintain consistency in strength and durability. The process of measuring the ingredients of each concrete mix to ensure consistency in strength, durability, density, homogeneity, water tightness and reduction of waste.

IMPORTANCE OF BATCHING OR PROPORTIONING Water to cement ratio Water-to-cement ratio is the gallons of water used per bag of cement. Four gallons per bag(cubic foot) is the typical ideal to mix the concrete completely, allowing complete hydration.

Water Water affects the hydration and improves the workability of cement. Water should be clean and free from organic materials, alkalis, acid, and oil. Portable water is suitable for mixing cement . Impurities in the water used for mixing can affect the setting time. It can cause surface corrosion and efflorescence of steel reinforcement.

BATCHING A batch is one mixing of concrete and can be carried out by two methods – volume and mass. Portland cement is packed in paper sacks, each weighing 94 pounds. A 94-pound sack of cement amounts to about 1 cubic foot by loose volume or 0.04m³ and a mass of 44kg.

BATCHING BY VOLUNE Concrete mixes are usually quoted by ratio such as 1:2:4. this is done by an open bottom box called GUAGE BOX. The box is filled with the specified proportions (should be able to hold one bag of cement); the top of the box is struck off level each time.

If the fine aggregate is wet, its volume will increase by up to 25%. The amount of fine aggregate should therefore be increase by this amount. This increase in volume is called BULKING.

BATCHING BY WEIGHT (MASS) This method involves the use of a scale which gives the exact weight of materials as they are placed in the scales. This method has a greater accuracy and the scale can be attached to a mixing machine.

Ready-Mix Concrete: Concrete that is not mixed on site, but which is batched at a central plant and delivered to the site by transit mixers.

Example Form size : 6’ x 4’ x 3”(3”/12” = ¼’ ) = 6 ft³ 0r 6/27 =yd³ Mix composition (ratio): 1:2:4 Add ratio : 1+2+4= 7 To find cubic feet Cement: 1/7 x 6=0.9 Sand: 2/7 x 6 = 1.7 Stone: 4/7 x 6 =3.4 With this ratio you will need 0.9 or 1cement, 1.7 or 2 sand, 3.4 0r 3½ stone NB. 5 – 6 buckets hold in a wheelbarrow. 1 bag cement holds 2½ buckets

CIRCULAR COLUMN CONCRETE VOLUMNE Formula : π x radius ² (sq. ft.) x height of column(ft) = ft ³/ yd ³ of concrete 27 (cubic ft/yd) Where π = 3.14 and radius = diameter (ft.) of column /2 NB. Inches are expressed as fraction or decimal equivalents. Step 1 : determine the radius of the column. E.g. 4 ’ /2 = 2 ’ Step 2 : calculate the volume using the formula π x radius ² (sq. ft.) x height (ft) = 3.14 x (2) ² x 30 27 (cubic ft/yd) 27 = 376.8ft ³ = 13.96 rounded up to 14 cubic yards 27 NB. For cubic yard, divide by 27. E.g. depth = 3 ½ (0.292 ’ ), form = 2 ’ x 4 ’ Concrete required = 2 ’ x 4 ’ x 0.292 ’ = 23.36 ft ³ or 23.36/27 = 0.865yd ³

DEFINITION FOR CONCRETE AND ITS USE A mixture of cement, sand, gravel and water in the correct/definite proportion to form a paste that can be moulded into any shape. Concrete is used to make columns, beams, etc.

DEFINITION OF MORTAR AND ITS USE Mixture of cement, sand and water mixed in correct/specific proportion. Mortar is used for making beds, for laying bricks and for rendering masonry walls.

The Five Types of Portland Cement Type I - Normal Type II - Modified Type III - High Early Strength Type IV - Low Heat Type V - Sulphate Resistant

TYPICAL APPLICATIONS & CHARACTERISTICS Type 1 This is known as general-purpose/normal cement for concrete that does not require any special properties. The design strength of Type 1 is 28 days and this duration is more than other types. It is used to build: Buildings • Reservoirs Bridges • Sewers • Culverts Masonry units •Tanks • Water Pipes Railways • Soil Cement Mixer

Type II Generates more heat than Type I. Used in larger pours, where the large volume and smaller surface area reduce the cooling ability of the pour such as drainage structures . Better sulfate resistance than Type I.

Type III Applications where high strength is required soon after pouring, such as when forms must be removed as soon as possible or in cold weather to reduce the need to protect the concrete from freezing. Type III cement has slightly less strength than other cements. It produces design strengths as early as 7 days.

Type IV Generates less total heat over a longer time period. Used in very massive pours, such as dams, large concrete structures and retaining walls. This cement has a low heat of hydration. It is used in structures having a minimal rate of heat of hydration. The strength of the cement develops at a lower rate than all the types. Design strength is reached in 90 days.

Type V Sulphates found in soils and water will attack the cement and produce cracks. Type V helps prevent this. It is used in concrete structures that are subjected to intense sulphate action. Design strength is reached in 60 days. It is used in areas with high sulphate content and underground tunnels.

SITUATIONS REQUIRING SPECIFIC TYPES OF CEMENT General Chemical deposits in soil Moisture levels Early development of strength Mass work

PLASTICS PROPERTIES OF PLASTICS Lightweight Rustproof Strong Can revert to their natural state Pliable Waterproof Non-conductor Good electrical insulators Good thermal insulators Good resistance to chemicals

USES OF PLASTICS IN CONSTRUCTION Electrical Conduits Water Seals Roofing Tiles Decorative Skirting Electrical Insulation Flooring tiles/finishes Water pipes Drainage pipes

SITUATIONS REQUIRING WATERPROOFING Basement Waterlogged soils (water penetration Damp proof (d.p.) course d.p membrane tanking

Damp-Proof Courses It is of the greatest importance that dampness be excluded from the interiors of buildings, on account of its detrimental effect upon the health of the inhabitants. Damp can enter a building in any of the following ways: (1) It may pass down through the tops of walls. (2) It may be caused by a driving rain passing through the surfaces of walls.

(3) It may be forced through walls and floors of basements in water-logged soils. (4) It may soak up from the footings of walls in damp soil. (5) It may be forced through the lower floors by the movement of ground air. (6) It may pass through the walls and floors of buildings from faulty drains, gutters, or rain-water pipes.

TIMBER AND TIMBER PRODUCTS CROSS-SECTION OF A TREE

Annual or growth rings - in temperate climates there are two distinctive growth seasons, spring and summer - the spring growth is rapid and is shown as a broad band whereas the hotter, dryer summer growth shows up narrow. In tropical countries the growth rings are more even and difficult to distinguish. Bark - the outer layer, corklike and provides protection to the tree from knocks and other damage.

Cambium - layer of living cells between the bast and the sapwood. Heartwood - mature timber, no longer carries sap, the heart of the tree, provides the strength of the tree. Usually a distinctive darker colour than the sapwood. Medulla ray - (rays) food storage cells radiating from the medulla - provides a decorative feature found in quarter cut timber.

Pith or medulla - the centre of the tree, soft and pithy especially in the branches. Sapwood - new growth carries the raw sap up to the leaves. Usually lighter in colour than the heartwood, especially in softwoods. Bast - the inner bark carries enriched sap from the leaves to the cells where growth takes place.

DISTINCTION BETWEEN HARDWOOD & SOFTWOOD Softwoods (gymnosperms). Softwoods are coniferous trees and the timber is not necessarily 'soft'. They are 'evergreen'. (The larch is an exception) Their general characteristics are: • Straight, round but slender, tapering trunk. • The crown is narrow and rises to a point.

It has needle like or scale-like shaped leaves and it's fruit, i.e. it's seeds are carried i n cones. • The bark is course and thick and softwoods are evergreen and as such do not shed their leaves in autumn. E.g. pine, bitter wood, redwood, cypress, red cedar, douglas fir, cedar damsel, yew, eucalyptus, sitka spruce, juniper, ginkgo

Hardwoods (angiosperms). Hardwood trees are broadleaf and generally deciduous. They shed their leaves in the autumn. Their timber is not necessarily hard. For instance, balsa (the timber used for making model planes) is a hardwood. The general characteristics are: • Stout base that scarcely tapers but divides into branches to form a wide, round crown.

The leaves are broad and may have single or multi lobes. • The bark may be smooth or course and varies in thickness and colours. • Its fruit may be: nuts, winged fruits, pods, berries, or fleshy fruits. E.g. lignum vitae, oak, sycamore, teak, ash, bulletwood, cotton, tamarind, white cedar, mahoganies, satin wood, mahoe, poplar

LUMBER CONVERSION Conversion is the cutting of log into marketable timber for commercial use. There are two main methods of converting timber: Through and through (or Plain or Crown sawn), which produces tangential boards and Quarter Sawn , which produces radial boards.

Quarter sawn (radial, figured) is far more expensive because of the need to double (or more) handle the log. There is also more wastage. It is however more decorative and less prone to cup or distort. Such timber is expensive due to the multiple cuts required to convert this board. Annual growth rings form an angle greater than 45 degrees.

Through and through produces mostly tangentially sawn timber and some quarter sawn stuff. Tangential timber is the most economical to produce because of the relatively less repetitive production methods. It is used extensively in the building industry

Tangential boards (crown, plain or flat sawn) are used extensively for beams and joists. They are stronger when placed correctly edge up with the load in the tangential axis. These type of boards suffer from 'cupping' if not carefully converted, seasoned, and stored properly. Annual growth rings form an angle less than 45 degrees.

Rift sawn is the cut which falls between crown and true quarter sawn. Quality floor boards are prepared from rift sawn timber because it wears well and shrinks less. Annual growth rings form an angle between 30 and 60 degrees.

SEASONING Seasoning is the controlled process of reducing the moisture content (MC) of the timber so that it is suitable for the environment and intended use. For construction grade timber the timber must be below 20% MC For framing and outside finish 15% MC For Cabinet and furniture 7 to 10% MC

METHODS OF SEASONING Air/Natural drying Air-drying is the drying of timber by exposing it to the air. The technique of air-drying consists mainly of making a stack of sawn timber (with the layers of boards separated by stickers) on raised foundations, in a clean, cool, dry and shady place. Rate of drying largely depends on climatic conditions, and on the air movement (exposure to the wind). Coating the ends of logs with oil or thick paint, improves their quality upon drying.

Kiln drying The process of kiln drying consists basically of introducing heat. This may be directly, using natural gas and/or electricity or indirectly, through steam-heated heat exchangers. In the process, deliberate control of temperature, relative humidity and air circulation is provided to give conditions at various stages of drying the timber to achieve effective drying.

For this purpose, the timber is stacked in chambers, called wood drying kilns, which are fitted with equipment for manipulation and control of the temperature and the relative humidity of the drying air and its circulation rate through the timber stack

MOISTURE CONTENT IN LUMBER Moisture Content A measure of the amount of water in a piece of lumber. The % MC is obtained by the formulae Wet weight – dry weight / dry weight X 100 = %MC (this is a standard scientific formulae for determining wood %MC)

DEFECTS IN WOOD A defect is any irregularity occurring in or on wood which reduces is strength, durability and usefulness. It may improve or reduces its appearance

Man Made Defects Bow : A curve along the face of a board that usually runs from end to end. Check : A crack in the wood structure of a piece, usually running lengthwise. Checks are usually restricted to the end of a board and do not penetrate as far as the opposite side of a piece of sawn timber.

Crook: Warping along the edge from one end to the other. This is most common in wood that was cut from the centre of the tree near the pith. Cup : Warping along the face of a board across the width of the board. This defect is most common of plain-sawn lumber.

Shake : Separation of grain between the growth rings, often extending along the board's face and sometimes below its surface. Split : A longitudinal separation of the fibres which extends to the opposite face of a piece of sawn timber.

Twist : Warping in lumber where the ends twist in opposite directions. Wane: The presence of bark or absence of wood on corners or along the length of a piece of lumber.

Machine Burn: Discoloration of the wood due to overheating caused by friction, and either scorching the wood or the resins within it. Machine burn is caused by stopping or not feeding the wood across the blades at the correct rate of speed. machine burn can almost always be prevented by using sharp blades and correct feed rates.

Natural Defects Blue Stain : A discoloration that penetrates the wood fibre. It can be any colour other than the natural colour of the piece in which it is found. It is classed as light, medium or heavy and is generally blue or brown.

Pitch: An accumulation of resinous material on the surface or in pockets below the surface of wood. Also called gum or sap. Loose /Dead Knot : A knot that cannot be relied upon to remain in place in the piece. Caused by a dead branch that was not fully integrated into the tree before it was cut down.

Tight/Live Knot : A knot fixed by growth or position in the wood structure so that it firmly retains its place in the surrounding wood. Spalt : Typically found in dead trees, spalting is any form of wood discoloration caused by fungi.

Wormhole: Small holes in the wood caused by insects and beetles. Dry rot is a condition of wood in which a fungus breaks down wood fibers and renders the wood weak and brittle.

Heart shake: Wood tissue separates due to uneven stress forming a crack. Star shake: This occurs where several shakes radiate from the centre region.

Ring or cup shake: This type of shake follows the line of the growth ring. The split occurs between two growth ring and is the result of uncontrolled seasoning. Resin pockets: Resin pockets do not affect the overall strength of the timber. They are more of a problem when it comes to machining and finishing the timber surface. The resin sticks to machine blades, eventually blunting them.

COMMON METHODS OF WOOD PRESERVATION Spraying or brushing with wood preservative Pressure treatment Dipping

EXPLANATIONS Pressure treatments force preservative into wood under higher than atmospheric pressures. Properly pressure treated wood is recommended for use in situations of high decay hazard (ground line contact). vacuum process: wood is placed in a sealed container and as much air is pumped out as is possible, creating lower than atmospheric pressure in the wood cells. Preservative is flooded into the tank and the seal is broken creating a partial vacuum which sucks preservative into the wood.

thermal process or hot-cold bath involves placing wood in a tank of hot preservative oil followed by immersion in cold preservatives. The hot bath heats and expands the air within the wood, forcing some of the air out. The wood is then immersed in the cold bath and the heated air contracts pulling preservative in with it. The thermal process is frequently used in treating utility poles

Cold soaking in solutions of creosote or penta has been moderately effective in treating round stock of species with thick, easily treated sapwood, such as that of many pines. Cold soaking should not be used when heartwood is exposed. Normal soaking times vary from 24 to 48 hours and there is little control over retention and penetration.

MANUFACTURED BOARDS Manufactured or man made boards - are made from wood products and have new/different properties to the wood they were made from. Board sizes are 8ft x 4 ft (2440 x 1220 mm).

MDF (medium density fibreboard) made by a process which glues wood fibres together using heat and pressure. The boards are smooth and strong. They are resistant to warping. MDF is used industrially for the production of furniture (especially shelves and cupboards),display cabinets, wall-panels and storage units. MDF is available in a range of thicknesses, 3mm, 6mm, 9mm, 12mm, 15mm, and 18mm.

Plywood is made from layers of thin wood glued together at 90 degrees to each other. There is always an odd number of veneers and the direction of the grain runs alternately to give the material strength Sizes : -Plywood is sold in 2440 x 1220mm and 1525 x 1525mm sheets. The most common thicknesses are 4, 6, 9 and 12 mm. Uses : -It may be used for wall panelling, flooring, furniture making , strong structural panelling board used in building construction. Some grades used for boat building and exterior work.

Chipboard is made by bonding together wood particles with an adhesive under heat and pressure to form a rigid board with a relatively smooth surface. Used for kitchen and bedroom furniture, kitchen worktops and carcases (cupboard shells). normally available in 2440 x 1220 sheets. Thicknesses range from 12 to 25 mm.

Hardboard (particle board) Hardboard is made from wood fibre is extracted from chips and pulped wood waste. In the production process the pulp is exploded under pressure. Heat and steam is applies to leave a fine, fluffy brown fibres. These fibres are transformed into mats, which are held together with lignum and other glues. The mats are than pressed between steam-heated metal plates to give grainless sheets with one smooth, glossy surface and one textured surface. Used for furniture backs, covering curved structures, door panels.

Blockboard is composed of a core of softwood strips (up to about 25mm wide) placed edge to edge and sandwiched between veneers of hardwood, the 'sandwich' is then bonded under high pressure. Used where heavier structures are needed. Common for shelving and worktops. Blockboard is normally available in 2440 x 1220 sheets (or subdivisions), thicknesses tend to be limited to around 30mm.

laminated board At first sight, edge laminated softwood board can look like one piece of timber, but it is actually made up of narrow (25 to 100 cm) strips of softwood glued edge to edge. This board is ideal for making furniture where the natural gain can be left exposed.

Bagasse is the fibrous matter that remains after sugarcane or sorghum stalks are crushed to extract their juice. Bagasse board Made from sugar cane.

PROPERTISE OF MANUFACTURED BOARDS Large sizes Uniform texture Smooth surfaces Standard dimension predictable quality Less warp

PIECES OF TIMBER IDENTIFICATION Baulk: square shaped pieces, about 100 mm wide and 50 mm or more thick. Planks : above 200 mm wide and between 38 and 100 mm thick. Flitches : 100mm x 300mm; not less Deals : 50mm x 100mm x 225-300mm maximum Battens : 50mm -100mm x 125mm - 200mm Slating and tiling : 16mm – 32mm x 25mm – 100mm

Panels : thin board slices Scantling : pieces about 75 mm wide by 50 mm thick. Strips Fillets : under 50mm, less than 100mm Quartering : square 50mm x 50mm, 150mm x 150mm, etc. Boards : more than 150 mm wide and less than 50 mm thick.

LUMBER CALCULATIONS Metric size lumber gives thickness and width in millimeters (mm) and length in meters (m). Metric lumber lengths start at 1.8m (about 6”) and increase in steps of 300mm to 6.3m (little more than 20’) metric lumber is sold by the cubic meter (m³) Formula a} T(mm) x W(mm) x L(m) b} T(mm) x W(mm) x L(mm) 1000 x 1000 x 1 1000 x 1000 x 1000

Another unit of measure for lumber is the Board Footage (bd. Ft.). When the size contains a mixed fraction, such as 1¼, change it to an improper fraction (5/8) and place the numerator above the formula line and the denominator below. Formula: T(in)xW(in)xL(ft) b) T(in)xW(in)xL(ft) 12 144

CAVEAT Nominal Size - Refers to the size of a piece of lumber before it is dressed and seasoned. It is used to designate a particular size piece of lumber, such as 2x4, 2x6, etc. Actual Size - Refers to minimum acceptable size after it has been dressed and seasoned. A nominal 2x4 can have a minimum actual size of 1.5 in. x 3.5 in. When referring to a specific piece of lumber, the nominal size is used. Length is not reduced by processing from the buyer.

IMPORTANCE OF INSULATION Insulation helps to: Hold down energy cost Control the temperature of the building Keep heat from entering the building

Insulation in construction involves materials that do not readily transmit energy in the form of heat, electricity or sound. Insulators are made from many materials, including cellulose, rock wool, a glassy lava called perlite, gypsum, certain plastics, fiberglass, asbestos, foam, insulating concrete, loose fills, quilt, insulating plasters, mica and refractory materials.

FIRE RETARDANTS A fire retardant is a material or substance other than water that reduces flammability of fuels or delays their combustion (burn slowly) . Gypsum CO 2 Paints Fibre wall boards rock wool asbestos cement perlite boards calcium silicate boards

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