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Flashcards in Substructure- Foundations Deck (21)
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1

What are the components of concrete?

Cement
Aggregate (fine/course)
Water

2

Why is concrete reinforced?

Strong in compression, weak in tension
Tensile forces will pull concrete apart concrete from bottom

3

What is and are the components of a strip foundation?

Suitable for most subsoils
Low to medium rise buildings (domestic)
Foundation can be reinforced

4

What is a raft foundation? Build up and what is it used for?

Covers entire footprint
Used when ground conditions are poor
RC to load bearing walls

5

What is an interlocking pile?

Similar to contig pile, gap filled with soft pile
Typically not reinforced, weak conc mix (c40)
Reduces water ingress
Cement/bentonite mix (1N/mm2)

6

What is a secant piled wall?

Similar to interlocking pile
Stronger concrete used for secondary pile 10N/mm)
Cost effective solution to diaphragm wall

7

What is sheet piling?

Steel sheet driven into the ground
Excavation performed once the perimeter is formed

8

What is the difference between displacement and replacement piling?

Displacement driven into the ground without excavation
Replacement is CFA piling

9

What is a retaining wall?

Used to retain or prevent material collapsing

10

What is a pile cap?

Links piles together through an RC cap
They can be linked through ground beams

11

What is a ground beam?

Links piles together for rigidness
Provides a platform for the superstructure

12

What is a ground bearing slab?

Typically the GF slab
Reinforced
Commonly supported by piles, caps and beams

13

How are earthworks supported and why?

o Temporary wooden supports
o Stop displacement or caving in of excavation
o Open or closed

14

Describe the different ways of dealing with ground water in excavations?

o Temporary or Permanent
o Permanant; impermeable barrier stops flow of water to the ground
o Temporary; lower water table through subsoil drainage techniques (sump pumps)

15

How was the substructure in the last question water-proofed?

Damp proof membrane

16

Explain activities involved when piling?

Measure in line with Section 1 of NRM1

Forming pile mat
Mobilisation/moving of pile rig
Pouring insitu RC piles
Cutting top of piles
Pile Caps
Pile testing
Pile casings if applicable

17

How would you increase waterproofing to concrete?

Waterproofing additive
Waterproof membranes

18

Why use secant wall piling and not contiguous?

Secant wall piling generally reduces the chance of water entry into the basement.

19

How do you construct a crane?

Mini Piles
Excavation
In Situ Concrete
Reinforcement
Erection of crane using mobile crane

20

Why would you use piling?

Subsoil is not strong enough to take the load bearing capacity of the superstructure

21

Basement grades

Grade 1 – Some water seepage and damp is tolerable depending on the intended use.
Grade 2 – No water penetration is acceptable
Grade 3 – No dampness or water penetration is acceptable