Types, Properties and Uses of Wood, Metals, Ceramics and Building Materials for JSS 1

Materials: Wood, Metals, Ceramics, and Building Materials

Performance Objectives

By the end of the lesson, students should be able to:

1. identify the properties of wood;
2. classify the properties of wood;
3. describe the properties of wood;
4. identify the properties of metals;
5. classify the properties of metals;
6. describe the properties of metals;
7. identify the properties of ceramics and glass;
8. identify various types of building materials in their locality;
9. mention uses of building materials.

Introduction to Materials

A material is any substance or matter that is used to make or build objects.

In everyday life, people use different kinds of materials to construct houses, manufacture vehicles, make furniture, and produce household utensils. These materials are selected based on their specific qualities, which are known as properties. The four major groups of materials used in technology and construction are wood, metals, ceramics, and general building materials.

Wood

Wood is a fibrous, porous structural tissue obtained from the stems and roots of trees.

It is a natural, organic material that has been used for thousands of years for fuel, construction, and paper production.

Properties of Wood

Wood can be identified and described by several physical properties. These properties determine how a particular type of wood can be used in construction or furniture making.

The primary properties used to identify and describe wood include:

1. Colour: Wood displays a wide range of natural colours, ranging from creamy white and pale yellow to deep red, golden brown, and dark brown.
2. Texture: This refers to the feel and appearance of the wood grain. Wood texture can be fine, medium, or coarse, and it can feel smooth or rough to the touch.
3. Density: This is the measure of how heavy the wood is relative to its size. High-density wood is heavy and compact, while low-density wood is light and porous.
4. Hardness: This is the ability of the wood to resist scratching, denting, and penetration by sharp objects.

Classification and Types of Wood

Wood is broadly classified into two main categories based on the botanical nature of the trees from which they are cut. These categories are hardwoods and softwoods.

Hardwoods

Hardwood is wood obtained from broad-leaved, deciduous trees, which are trees that produce seeds enclosed within a fruit or nut.

These trees grow slowly, resulting in a dense, compact, and hard wood structure. Hardwoods are generally heavy, highly durable, and resistant to wear.

Examples of hardwoods commonly found in Nigeria include:

1. Mahogany: This wood has a rich reddish-brown colour and a fine, even texture. It is highly dense, strong, durable, and resistant to wood rot.
2. Opepe: This wood is easily recognized by its distinct golden-yellow to orange-brown colour. It has a coarse texture, is extremely hard, and is highly resistant to decay and insect attack.
3. Mansonia: This wood has a dark grayish-brown colour, resembling walnut. It has a fine texture, is very hard, and is used for high-quality joinery.

Softwoods

Softwood is wood obtained from coniferous trees, which are trees that have needle-like leaves and produce cones.

In tropical regions like Nigeria, the term is also used to describe light-density woods from certain broad-leaved trees. Softwoods grow relatively fast, making them lighter, less dense, and softer than hardwoods. They are easier to cut, nail, and work with.

Examples of softwoods and light-density woods include:

1. Obeche: This wood is creamy-white to pale yellow in colour. It has an open, coarse texture, is very lightweight, and is very soft. It is easy to carve and shape.
2. Afara: This wood ranges from straw-coloured to light brown. It has a medium texture, is moderately soft, and is lightweight but stronger than Obeche.

Metals

Metals are mineral substances extracted from ore in the earth that are typically hard, shiny, and excellent conductors of heat and electricity.

Metals play a critical role in engineering, manufacturing, and construction due to their strength and durability.

Identification of Metals by Physical Properties

Metals can be identified and distinguished from non-metals by observing specific physical properties.

The key physical properties of metals are:

1. Lustre: This is the ability of a metal to reflect light, giving it a shiny appearance when polished.
2. Density: Most metals have high density, meaning they are heavy and feel solid when lifted.
3. Sound (Sonority): Metals produce a clear, ringing sound when struck by another hard object.
4. Malleability: This is the property that allows a metal to be hammered, rolled, or beaten into thin sheets without cracking or breaking.
5. Ductility: This is the property that allows a metal to be drawn or pulled out into thin wires.
6. Thermal and Electrical Conductivity: Metals allow heat and electric current to pass through them easily.

Forms of Metals

After extraction and processing, metals are shaped into various commercial forms for use in industries and construction sites.

Common commercial forms of metals include:

1. Rods: Solid, cylindrical metal bars used for structural reinforcement.
2. Bars: Solid metal pieces with square, rectangular, or hexagonal cross-sections.
3. Pipes: Hollow, cylindrical metal tubes used to transport water, gas, and other fluids.
4. Wires: Thin, flexible strands of metal used for electrical wiring and binding.
5. Plates: Thick, flat pieces of metal used in heavy construction, such as shipbuilding and bridge building.
6. Sheets: Very thin, flat pieces of metal used for making roofing sheets, car bodies, and metal containers.

Ceramics and Glass

Ceramics are non-metallic, inorganic materials made from clay and baked in an oven or kiln at very high temperatures.

Glass is a hard, transparent or translucent material made by melting silica sand with other minerals at extremely high temperatures and then cooling it rapidly.

Types and Examples of Ceramics and Glass

Ceramic and glass products are widely used in homes, offices, and laboratories.

Common examples of ceramic and glass products include:

1. Bricks: Baked clay blocks used for building walls.
2. Tiles: Flat ceramic pieces used for covering floors and walls in kitchens and bathrooms.
3. Bottles: Glass containers used for storing drinks, medicines, and chemicals.
4. Cups and Plates: Ceramic tableware used for eating and drinking.
5. Pots: Traditional clay pots used for cooking, cooling water, and decoration.

Properties of Ceramics and Glass

Ceramics and glass share several unique properties that make them suitable for specific applications where metals and wood cannot be used.

The main properties of ceramics and glass include:

1. Brittleness: They are hard but break easily into pieces when dropped or subjected to sudden impact.
2. Heat Resistance: They can withstand very high temperatures without melting, burning, or losing their shape.
3. Electrical Insulation: They do not conduct electricity, making them safe for use as electrical insulators.
4. Chemical Resistance: They do not rust, corrode, or react with water, acids, or other chemicals.

Building Materials

Building materials are substances used in the construction of houses, roads, bridges, and other physical structures.

These materials can be natural, such as wood and sand, or man-made, such as cement and plastics.

Common Building Materials in the Locality

Different building materials are used depending on the type of structure, the climate, and the resources available in the local environment.

Common building materials found in Nigerian communities include:

1. Cement: A grey powder made from limestone that sets and hardens when mixed with water.
2. Sand: Fine granular particles of rock used to make mortar and concrete.
3. Gravel: Small, loose stones or pebbles used to provide strength to concrete.
4. Metal: Iron rods and steel sheets used for structural strength and roofing.
5. Plastics: Synthetic materials used for plumbing pipes, electrical fittings, and ceiling panels.
6. Wood: Timber used for roofing frames, doors, windows, and concrete support.
7. Glass: Transparent sheets used for window panes and doors to allow light into buildings.
8. Leaves: Natural palm fronds or raffia leaves used for traditional thatch roofing in rural areas.
9. Ceramics: Clay bricks, floor tiles, and sanitary wares like washbasins and toilet bowls.
10. Grass: Dried grass or straw used for traditional thatch roofing and wall insulation.

Uses of Building Materials

Each building material has specific properties that make it suitable for particular parts of a building structure.

The primary uses of common building materials are:

1. Cement: It is mixed with sand, gravel, and water to form concrete, which is used for foundations, pillars, and beams. It is also mixed with sand and water to make mortar for binding blocks together and plastering walls.
2. Sand: It is mixed with cement to make plaster for walls and mortar for laying blocks.
3. Gravel: It is mixed with cement, sand, and water to create strong concrete that supports heavy loads.
4. Metal: Steel rods (rebar) are placed inside concrete to reinforce pillars and floors. Aluminum or zinc sheets are used as roofing materials.
5. Plastics: Polyvinyl Chloride (PVC) pipes are used for water supply and drainage systems. Plastic conduits are used to protect electrical wires.
6. Wood: It is used to construct the roof framework (trusses), doors, window frames, and wall panels. It is also used to make temporary scaffolds during construction.
7. Glass: It is fitted into window and door frames to allow natural light into rooms while keeping out wind and rain.
8. Leaves and Grass: They are woven together to make thatch roofs for traditional houses, providing natural cooling in hot climates.
9. Ceramics: Floor and wall tiles are used to cover surfaces to make them easy to clean and visually appealing. Clay bricks are used to build durable walls.

Practical Skills: Sorting and Proper Use of Materials

How to Sort Building Materials

Sorting building materials helps to organize a construction site, prevent accidents, and keep materials in good condition.

The procedure for sorting building materials involves the following steps:

1. Identify the material group: Group the materials into wood, metals, ceramics, plastics, and loose aggregates (sand and gravel).
2. Separate by form: Group metals into rods, pipes, and sheets. Group wood into planks, beams, and plywood.
3. Store loose materials: Heap sand and gravel in separate, clean areas to prevent them from mixing with soil or rubbish.
4. Protect sensitive materials: Stack bags of cement on raised wooden platforms and cover them with waterproof tarpaulins to keep them dry.
5. Store fragile materials safely: Place ceramic tiles and glass sheets upright in secure crates to prevent them from cracking or breaking.

Proper Use and Maintenance of Materials

Using materials correctly and maintaining them properly ensures that structures remain safe and durable.

Guidelines for the proper use and maintenance of materials include:

1. Wood: Wood should be treated with chemical preservatives to protect it from termites and wood-boring insects. It should be kept dry to prevent rotting.
2. Metals: Metals should be painted, greased, or galvanized to prevent rust and corrosion caused by exposure to air and moisture.
3. Ceramics and Glass: These materials should be handled gently during installation. They should not be subjected to heavy impacts or sudden temperature changes.
4. Cement: Cement must be kept completely dry before use. Once mixed with water, it must be applied quickly before it sets and hardens.