Bricks and Blocks Flashcards
(29 cards)
What are the 2 materials that bricks can be made from
Clay or Calcium Silicate
What is the standard size of a brick
215 x 102.5 x 65 mm
Laid with a nominal 10mm mortar joint
What are the 3 shapes of bricks
- Solid
- Frogged
- Perforated
What are the 3 brick types and describe them
- Common, these are generally used on the inside of buildings
- Facing, used on the outside as made to look nice on one face through textures and colouring
- Engineering, strong and dense- these have a lower water absorption and therefore are used near the bottom
Describe the process of making Clay bricks
- Prepared by winning (extracting from a quarry) clay from the ground
- Clay is ground down and water is added
- Mixing
- Shaping by extrusion, clay loaded into an extruder in a vacuum chamber
- Drying, 1 day at 110 C removes water
- Firing, 3 days at 1050 C particles fused together
Describe the process of making calcium silicate bricks
- Winning sand or crushed flint
- Mixing with lime
- Pressing
- Autoclaving, high pressure steam 170 C
Testing:Compressive strength is given as a mean of how many bricks
10
Testing: Dimensions of a brick are given as a mean of how many specimens
24 placed end to end
What is mortar
It is a gap filling glue. It distributes loads between separate walling components so they act as a unit
What is mortar made from
Normally from sand and binder, in the ratio 3 parts sand to 1 part binder. The binder is generally cement and/or lime
Properties of mortar
- Good Plasticity
- Able to retain its water against the suction of the bricks against which its being laid
- Mix shouldn’t separate
- Once hardened should exhibit similar moisture and thermal properties to the bricks its laid on
- Once laid should develop its strength quickly
If the ratio of cement in the mortar increases how do the properties of mortar change
- Strength increase
- Quicker stiffness
- Greater frost resistance
- Less risk of sulphate attack
- Less risk of rain through the mortar
If the ratio of lime in the mortar increases how do the properties of mortar change
-More working time
-Greater workability
-Greater flexibility
Less rain through joints
What percentage of a wall is brick and what percentage is mortar
88% brick 12% mortar
What are the 3 different ways brickwork can be constructed
- Stretcher- all bricks laid length ways
- English- one row all length ways, the next all width ways
- Flemish- Alternate between length and width
What are cavity walls
A wall formed from2 thicknesses of brickwork with a space between them
Why are cavity walls sometimes used
Damp penetration and Insulation
Desirable properties of brickwork
Thermal Insulation
- Sound Insulation
- Resistance to fire
What are the 4 problems with brickwork
- Efflorescence
- Sulphate Attack
- Frost Attack
- Water Ingress
What is Efflorescence
Water dissolves salt in brick, causing it to migrate to the surface, when the water evaporates it leaves salt as a surface deposit
What is sulphate attack
Water dissolves soluble sulphates in the brick, the solution then migrates to the mortar. The sulphates attack the tri-calcium aluminate in the mortar, causing it to expand and crumble
What is frost attack
Bricks absorb water and then freeze, as it freezes it expands and forces off the surface of the brick
How can water ingress be prevented
Using Damp Proof Course (DPCs), engineering blocks
or Damp Proof Membranes (DPMs) polythene sheets of coping stones
Difference between jointing and pointing brickwork
Jointing is the operation of making and finishing the joints between bricks, whereas pointing is the process of raking out the exposed jointing of brickwork and refilling
