information on foundations used in construction

1. Learning out comes
foundations and floors
The learner will be able to
summarise the need for foundations
How trenches are dug
List the different types of foundations
List the materials used in the construction of
foundations and floors

2. Foundations
These are the main part of the substructure, where would you find them?
These are an important part of the building, what
do they do?
Spread the load of the building
At planning stage the area is surveyed and the soil checked
to determine the depth width and size of foundations, this is
vital as the wrong foundations could result in?
The building subsiding or even collapsing
The soil is even tested for chemical contamination, why is this?
There are 4 main types used in the construction of buildings
The part of the building below DPC , dug into the ground.
Some types of contamination could affect the materials being used.
Narrow strip Wide strip raft pad

3. Concrete ground floor slab
insulation
Damp proof membrane
Cavity fill
Trench filled with concrete
To specification requirements
Damp proof course
Atmospheric
depth
Narrow strip foundation
The most commonly used type of
foundations used
Name the components that make up strip foundations.
Give an explanation for each component?

4. Component parts of a strip foundation
Concrete slab
insulation
Cavity fill
Trench fill
Damp proof course
Finished floor level (FFL)
Material used to prevent heat loss, or cold rising from below
To prevent compression of brickwork
below damp course level
Concrete that is poured into the trench to produce the foundation
Placed a minimum of 150 mm above ground level to prevent
Moisture rising above the finished floor level

5. Mild steel reinforcement
transverse bars
Damp proof course
Minimum of 150mm
Cavity fill
Longitude bars
Concrete strip
foundation50mm concrete blinding
backfill
Why are these type of foundations used?
If the building is heavy or the soil is
not very stable
Wide strip foundation
What is the purpose of the reinforcing rods in the concrete?
To bind the concrete together

6. Floor screed
insulation
Steel reinforcing
matting
insulation
DPC
75mm
blinding
Raft foundation
Give an explanation of the term BLINDING in relationship to construction?
Material used (usually sharp sand or ballast ) to cover any
cavities, gaps or sharp edges to give a flat surface.
This type of foundation is
used when?
Where very poor soil conditions
are found.

7. Pad foundation
Where pads are placed at
Strategic points, with concrete
Beams placed across the pads to
Spread the load.
How are concrete pads different
To strip foundations?

8. Piled Foundations
drilling into the ground down to bedrock getting ready to fill with
reinforced concrete.
How are piled foundations made?

9.  Increasingly being
used even where
there are no ground
problems, for reasons
of speed and
economy
 Usually used with
precast beam and
block ground floors
 Rare in older
properties
Foundation Design –
Short bored pile foundations
What are the benefits of
Using this type of foundation?

10. Trench Foundations
Digging the trench with a JCB Filling the trench with concrete
Explain what is happening in these pictures?

11. Finished trench Foundations

12. Materials used in foundations and floors
Aggregates, this is a collective name for?
These can be further classified into two groups?
Fine aggregates that can pass through a 5mm sieve
These include?
building, washed, soft and sharp sands.
And used to make?
Mortar and concrete.
Sand may be obtained from?
Pit’s, riverbeds or dredged from the sea.
and
Coarse aggregates.
Are aggregates that are?
Retained by a 5mm sieve.
These particles can go from 5mm to 40mm
The most common coarse aggregate is limestone chippings.
This type of aggregate is used to make?
Concrete.
Sand and ballast

13. Types of cement
Cement is?
A powder which is made from chalk and clay and is added to sand and ballast
Through a chemical reaction when water is added the mixture turns hard.
There are many different types of cement powder, so depending on the job
Selecting the correct type is essential.
O.P.C? what does this stand for and where would you use it?
Ordinary Portland cement.
Concrete , mortar and grout.
R.H.P,C? what does this stand for and why would you use this?
Rapid hardening Portland cement.
High early strength is required.
S.R.C? what does this stand for and what is it’s special qualities?
Sulphate resisting cement. Used for concrete exposed to?
Sulphate attack i.e below ground level.