Clay and clay production in civil engineering

1. CHAPTER FIVE:
CLAY AND CLAY PRODUCTS
Clays: - are finely grained soils resulted from decay of rocks.
Chemical constituents of clay
There are different types of chemical constituents of clay and
some of them are:
 Silica (Si O2)
 alumina silicate (A12O3. 2Sio2.2H2O)
 Ferric Oxide (Fe2O3)
 Lime (Cao)
 Magnesia (Mgo)
 Carbon dioxide (Co2)
 Alkalies, water, etc

2. BRICK
 Are building materials manufactured from clays (raw material)
 Are most extensively used materials of construction because of
their strength, durability…
Raw material
 A clay soil for brick making should be prepared with water &
it can be molded, dried and burnt without cracking. Such
material should preferably have the following composition:
Clay 20 - 40%
Sand 30 - 50%
Others (lime, silt, cement, etc.) - 20 - 35%

3. MANUFACTURE OF BRICKS
 Raw material (clay) should be excavated and crushed
it must be free of stones, boulders, coarse sand or lime.
 Mix it with water to the desired consistency.
Mix it until the whole mass becomes homogenous and plastic
 Then fed in to moulds made of timber or metal or pressed and
cut to desired length. The brick at this stages is called green
brick
 Drying green brick
 Burning: - (900 - 12000c) in a kiln
 Cooling: two to three days for kiln burnt bricks
 Then we have the brick.

4. TYPES OF BRICKS
 Two types of clay bricks are manufactured in Ethiopia at
present. These are:
1) Solid clay bricks
2) Hollow clay bricks and beam tiles.
 Solid clay bricks: a) brick without holes or depression.

5. TYPES OF BRICKS
 b) Hollow clay bricks: brick with holes up to 20mm  each and Area of holes 25%
 Nominal dimensions: 6 x 12 x 25 cm
Tolerance  0.25,  0.5,  0.81 cm

6. CLASSES OF BRICKS
 Adobe brick - brick that is not burnt in a kiln at all.
- Traditional
- adding lime increases bonding
 Sand-lime brick - not burnt at high temperature.
- Cement can sometimes be used.
 Kiln burned brick - brick burnt at high T0.
 Concrete bricks - is like a concrete block
- Relatively coarser agg. (6mm ) is used.
- are lighter in wt than concrete blocks - less density.
- are fire resistant.
- less sound transmission.

7. TYPES OF BRICKS (DEPENDING ON FUNCTION)
 Common bricks - for general building purpose.
 Facing bricks - with a better quality control - for better
appearance.
 Glazed face bricks - have shiny characteristic due to spraying
of some salts which results a shiny luster after burning.
 Firebricks - bricks for fire resistance.

8. Types of brick…
 Engineering brick- fired clay brick,having a dense and strong semi-vitreous
body,conforming to defined limits for water absorbtion and compressive
strength
 Frogged brick-Frogs not exceeding 20% of gross volume
 Soft mud bricks- most economical,burned at 900-1000 C0 to achieve
strenght.
 Dry pressed bricks-more accurate,sharper-edged bricks

9. TYPES OF BRICK…
 Extruded bricks-hard dense,lighter,easier to handle,different
thermal properties from solid bricks.make hardened by drying
20-40 hours at 50-150 C before being fired.
 Calcium silicate bricks-consist of lime,mixed with quartz ,
crushed flint or crushed siliceous rock with mineral colourants.
Bricks are accurate ,uniform, various colors( white is
common)

10. USES OF BRICK
 In metalurgy industry , glass industry
for lining furnaces.
 Use as a refractory (silica, magnesia
bricks)
 To make walls, fences etc..

11. GENERAL PROPERTIES OF BRICK
 Hard
 Durable
 Rectangular
 Smallish
 Holds heat well/insulates
 Compact
 Come in several earth-tone colors
 Cheap