G3 - Concrete Formwork - Describe Footing Forms

Question 1

When can footings be cast in excavated forms?

Answer 1

Once the soil is stable enough.

Question 2

List three requirements for footings.

Answer 2

1) Correctly positioned
2) Accurately dimensioned
3) Level

Question 3

How are the inside forms positioned once simple outside footing forms are in place?

Answer 3

Spaced and nailed to the outside of form using cleats

Question 4

Explain the wrap-around method of building square column footings:

Answer 4

All 4 sides cut to the same length.

Question 5

What type of footing is used under a concrete wall?

Answer 5

Continuous strip footing

Question 6

What type of footing form must be securely weighted or staked down to keep it from floating when the fresh concrete is placed into it?

Answer 6

Tapered pier footing.

Question 7

Why is the wrap-around type of pad form economical?

Answer 7

Boards need not be cut

Question 8

When is a raft slab used and how does it work?

Answer 8

When soil has a low bearing capacity it’s a long way down to firm soil. The raft slab uses the entire slab to act as the footing.

Question 9

What does it mean to preload the site?

Answer 9

Large and heavy amounts of rocks compress and consolidate the soil before building a future building. It has the same weight as future building.

Question 10

How is buoyancy used to float a building?

Answer 10

A deep raft slab & concrete wall are used to displace enough soil by weight to equal the weight of the building placed on the foundation.

Question 11

What is a mass slab footing?

Answer 11

A mass slab footing is a heavy block of concrete. Usually the size of the footprint of the building & is quite thick. It is used to anchor down a “ballast” tall building.

Question 12

What is a simple footing form?

Answer 12

Form boards, held in place with wooden or steel stakes.

Form boards are tied together with wooden cleats(straps), the cleats also act as spreaders to keep the footing width uniform.

Question 13

How high should you set footing forms?

Answer 13

A little higher than the proper elevation, so they are a proper height after stakes are pounded down.

Question 14

Footings that support a foundation wall are:

Answer 14

Continuous and usually referred to as - continuous strip footings.

Question 15

Strip footings are placed where? under a foundation wall.

Answer 15

Centered directly under the foundation wall.

Question 16

Keyway blackouts should be angled on the sides at:

Answer 16

15 degree to 20 degrees

Question 17

What is an important practice with Tapered Pier footings?

Answer 17

Tapered column footing forms need to be weighted down to resist the upward push of the fresh concrete.

Question 18

When the bearing capacity of the soil is low, and the distance down to firm bearing is too great, what foundations are used?

Answer 18

Raft slab, piles, and caissons.

Question 19

How do deal with differential settlement?

Answer 19

Preload the site with large piles of rock, gravel, or heavy materials weighing the SAME amount as the future building + contents. Leave for 6 months or more, until soil is sufficiently compressed and consolidates the soil.

Question 20

What is a caisson?

Answer 20

Large diameter pile that is made of concrete cast in place. Piles may be wood, steel, or concrete and may be driven or cast in place.

Question 21

Answer 21

Narrow U stairs

Question 22

Answer 22

Narrow U stairs