Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Define and classify different types of bricks and cement.
• Describe the key properties of these materials.
• Explain how these properties affect a structure's performance.
• Compare the advantages of using different materials.
• Select appropriate materials for a specific situation.

Lesson summary

Civil Technology relies heavily on understanding the properties of construction materials. This week, we'll be focusing on three fundamental building blocks: bricks, cement, and aggregates. These materials, when properly combined, form structures that shape our environment, from homes and schools to roads and bridges. In South Africa, with its diverse climate and ever-growing infrastructure needs, understanding these materials is critical for ensuring safe, durable, and cost-effective construction. Think about the houses in your community – understanding the materials used to build them helps us appreciate the challenges and solutions employed in providing shelter.

Lesson notes

2.1 Bricks Bricks are a fundamental building material used for walls, pavements, and other structures. They are typically made from clay or shale, which is molded into shape, dried, and then fired in a kiln.

Types of Bricks: Clay Bricks: The most common type. The properties of clay bricks depend on the type of clay used and the firing temperature.

Common Bricks:* Used for general construction, often in internal walls or areas where they will be covered. Lower quality, may have imperfections.

Face Bricks:* High quality, uniform in size and color, and used for exposed exterior walls. Contribute to the aesthetic appeal of the building.

Engineering Bricks:* Very strong and durable, with low water absorption. Used in situations requiring high load-bearing capacity or resistance to frost and chemical attack, such as foundations or retaining walls.

Concrete Bricks: Made from cement, aggregates, and water. They are cured rather than fired.

Advantages:* Consistent size and shape, readily available.

Disadvantages:* Can be less aesthetically pleasing than clay bricks, may have higher water absorption. Calcium Silicate Bricks (Sand Lime Bricks): Made from sand, lime, and water, and hardened by autoclaving.

Advantages:* Good dimensional accuracy, smooth surface.

Disadvantages:* Not as resistant to acids as clay bricks.

Properties of Bricks: Strength: Measured by compressive strength (the amount of force a brick can withstand before crushing). Engineering bricks have the highest compressive strength. This is tested using a crushing machine in a lab, and reported in MPa (MegaPascals).

Durability: The ability of a brick to withstand weathering, chemical attack, and abrasion. High-quality bricks are more durable. Consider buildings in coastal areas of KwaZulu-Natal which are subjected to salty air. These require more durable bricks.

Water Absorption: The amount of water a brick absorbs when immersed in water. Low water absorption is desirable to prevent damage from freezing and thawing. For example, bricks with high water absorption will be susceptible to cracking in areas with cold winters (e.g. Drakensberg region).

Size and Shape: Bricks should be uniform in size and shape to ensure ease of construction and a neat appearance.

Sound Insulation: The ability of the brick to reduce noise transmission. Higher density bricks tend to offer better sound insulation.

Thermal Insulation: The ability of the brick to retain heat or keep heat out.