Bricks

Question 1

How are bricks produced?

Answer 1

Raw clay (containing 25-30% silica sand) is mixed with water adn pressed into steel molds with a hydraulic press. The shaped clay is then thrmally treated at 900-1000 dC, this is called sintering.

Question 2

Explain sintering

Answer 2

Sintering is when the particles if the ceramic powders are pressed together at the same time as the temperature raises which causes diffusion of the particles. This reduces void content, but bricks have typically 20-25% porosity left.

Question 3

How can you form bricks?

Answer 3

Dry pressing
Extrusion

These shaping steps are done before sintering.

Question 4

What content can consider a brick “normal”?

Answer 4

Silica (25-30%), alumina, lime, iron oxide, magnesia

Question 5

When can sintering be performed at low temperatures?

Answer 5

If lime or glass are added, they allow a lower melting point

Question 6

Is it good to have roughness or porosity in the bricks?

Answer 6

Yes this can be seen as good since it ensures good adhesion of the mortar in wall constructions. Holes does not provide any problem in ceramics, different form stones.

Question 7

What is the use of bricks?

Answer 7

Materials fro industrial applications
External paving
Buildings

Question 8

What is exotic pores?

Answer 8

A way to improve the moisture buffering and the internal comfort in the building by making layers of the pores in a non structural way. Moisture is then absorbed by the high porosity of the bricks.

Question 9

How can weathering of bricks occur?

Answer 9

Gelivity: Can be reversible or irreversible
Crystallization of soluble salts: Salts crystallize in the pores when the water evaporates and creates pressure on the walls. Can come from rain, snow, capillary rising but also from inside the bricks and the different chemicals there.

Question 10

How can we solve the problem with water penetrating inside the bricks?

Answer 10

• Hydrophobic coating
• Impermeable coat like a plastic sheet underground to avoid the direct contact between wall ans solid
• A kap on top
• Render = puts

Question 11

How can we remove the water form the brick wall?

Answer 11

By using electro osmosis

1. Capillary rising
2. Electrode application
3. Movement of water
4. New plaster on te wall

Question 12

What are the advantages of electro osmosis?

Answer 12

the removal of soluble salts during restoration, drying the wall reduces the risk of corrosion, cost effective.