Brick Manufacturing Process Quiz

Construction Materials and Equipment (CENG-2081)

• Course is about construction materials and equipment.
• Specific focus on stone-bricks-concrete blocks.

Chapter 1: Stone-Bricks-Concrete Blocks

• Introduces different types of construction materials.
• Starts with a detailed study of bricks.

Bricks

• Bricks are a popular building material because they are cheap, durable, and easy to handle and work with.
• Bricks are used in exterior and interior walls, partitions, piers, footings, and other load-bearing structures.

Introduction to Bricks

• Bricks are rectangular.
• They come in various sizes, that are convenient for use. (19x9x9 cm, 19x9x4 cm)
• Brick materials can include burnt clay, mixture of sand and lime, or Portland cement concrete..
• Availability and cost-effectiveness make clay bricks a common choice.

Size of a Brick

• Standard size: 19cm x 9cm x 9cm or 19cm x 9cm x 4cm.
• When placed in masonry with mortar, a standard brick's overall size becomes 20cm x 10cm x 10cm (field bricks).
• The dimensions of bricks are relevant for construction work.
• Length of brick = 2 x width of brick + thickness of mortar. Height of brick = width of brick.
• Indent, called frog (depth 1-2cm) on the brick.

Composition of Brick

• Key constituents are silica (50-60%), alumina (20-30%), lime (4-5%), Iron oxide (5-6%), and Magnesia (1%).
• These elements are essential for making quality bricks.

Manufacturing of Bricks

• Consists of 4 steps:
  • Preparation of Brick Earth
  • Moulding
  • Drying
  • Burning
• (1) Preparation of Brick Earth*
• Unsoiling: Removal of the top 200mm of soil.
• Digging: Extraction of clay from the ground. The clay is levelled and prepared in heaps (60cm-120cm height).
• Cleaning: Removal of stones, pebbles, or other impurities from the clay. Washing and screening are used if needed.
• Weathering: The clay is exposed to the weather (rain, sun, wind) for a few weeks/full season. This process is known as weathering.
• Blending: Mixing/loosening clay for proper combining of ingredients and achieving uniformity and removing impurities.
• Tempering: Process to bring clay to required hardness and preparing it for moulding, done via adding water to the clay (via feet of men or cattle).
• (2) Moulding*
• The process of shaping the brick using moulds.
• Hand moulding: Using manpower to shape bricks. Different types exist (Ground, Table).
• Machine moulding: Utilizing machines to produce bricks (Plastic clay and Dry clay machines).
• Types of moulds: Wooden moulds and Steel moulds
• (3) Drying*
• This is a process where damp bricks or green bricks are dried before burning to prevent cracking and distortions.
• Duration (7–14 days).
• Bricks are placed along the edges, not the face during drying to speed the process.
• (4) Burning*
• Brick burning is done in specific temperatures (1100°C ) making the brick more dense.
• Over burnt/under burnt bricks can lead to improper quality and results.
• Burning occurs in 3 stages (Dehydration/Water smoking stage, Oxidation period, Vitrification).
• Different techniques exist (Clamps and Kilns).
• Clamp burning: Trapezoidal shape with ends raised at 15 degrees.
• Kiln burning: Large ovens used to burn bricks.

Classification of Bricks

• Unburnt/Sundried Bricks: temporary, used in places with less rainfall.
• Burnt Bricks: further categorized into 4 grades (including first class, second class, third class, and fourth class) based on quality.
• First class: table moulded, sharp edges, used for permanent work.
• Second class: ground moulded and burnt, may have irregular edges, used for walls plastered later.
• Third class: ground moulded and burnt in clamps, used for temporary/unimportant, less rainfall.
• Fourth class: overburnt bricks, irregular shape and dark colour. Used in concrete foundations, floors and roads as aggregates.

Qualities of a Good Brick

• Free from cracks and sharp edges.
• Uniform shape and standard size.
• Sound when struck together
• Compact.
• Minimum water absorption when soaked for 24 hours (1st class max 20%, 2nd class max 22% by weight).
• No impression when scratched with a fingernail.
• Low thermal conductivity, good sound proof properties.
• Dropped from 1m and won't break in half.
• No white salts when dried in the shade
• High crushing strength (>55 kg/cm2)

Tests on Bricks

• Compressive strength test: Determining the strength of the bricks using machines by recording pressure needed to break.
• Water absorption test: Measuring the percentage of water absorbed (max 20% for 1st class.
• Efflorescence test: Identifying presence of impurities (alkalies.)
• Hardness test: Assessing strength against abrasions.
• Soundness test: Detecting soundness by checking the clear metallic ringing sound.
• Structure test: Detecting the quality of bricks on broken faces (cracks, voids).

Concrete Blocks

• Concrete is a composite material created by mixing cement, aggregate and water.
• Masonry unit made from a different material mixture.
• Concrete blocks are produced by machines (Block making machines).

Classification of Concrete Blocks

• Solid blocks: No cavities, voids less than 25%.
• Cellular blocks: One or more voids.
• Hollow blocks: Common type, voids up to 50% (Types include Stretcher, Corner, Pillar, Jamb, Partition, Lintel, Brick, Bull nose).

Advantages of Concrete Blocks

• Lightweight (using lightweight aggregate).
• Less mortar needed.
• Quicker construction.
• High seismic resistance (can fill voids with steel bars).
• Good thermal insulation.
• Use for electrical and plumbing installations.

Materials for Concrete Blocks

• Cement: OPC, Portland blast furnace slag, sulfate resisting.
• Aggregate: Coarse aggregate (Max. particle size 13 mm). Rounded or angular particles have differing affects (flow and strength).
• Water: Enables chemical reactions. Lubricates mixture.

Production Process

• Proportioning: Measuring suitable amounts of raw materials.
• Mixing: Combining raw materials into homogeneous mix.
• Compacting: Consolidating mix in molds (using machines like Egg-laying/Auto stationary).
• Curing: Maintaining moisture and temperature (7–14 days) for concrete to reach the desired strength.

Tests on Concrete Masonry Blocks

• Various tests to meet all the requirements (Dimension measurement; Compressive strength.)
• Dimension measurement: Measuring length, width and height.
• Compressive strength test: Taking average max load in Newton's divided by the gross cross section area in square millimetre. Minimum required strength for different classes of concrete blocks.