Construction Tech Flashcards

1
Q

Bonded Screeds

A

which are laid on to a ready prepared rough, cleaned concrete base.

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2
Q

Unbonded Screeds

A

which are laid on to a sound clean bitumen damp proof membrane.

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3
Q

Floated Screed

A

which is laid with steel or fibre reinforcements on to the insulating board, which in turn can be laid on to a suitable damp proof membrane.

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4
Q

Resin bonded screed

A

which is laid on to a clean, rough pre-prepared concrete base. The resin acts as a ready installed damp proof membrane to the top screed.

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5
Q

Sheet piles

A

a. Deep trench is excavated and concrete is poured in situ
b. Piles can be used to form basement walls or act as retaining walls

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6
Q

Secant Piles

A

a. Interlocking piles provide a combination of foundations and basement walls
b. Support in providing a waterproof structure and are often seen when top down construction methods are used

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7
Q

Bored piles

A
  1. Bored piles
    a. An auger is used to excavate the soil and then concrete is poured once complete
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8
Q

Pre-cast piles

A
  1. Pre-cast piles
    a. Hammered into the ground (not often favoured due to high noise and lack of flexibility in depth)
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9
Q

What are the different ways that the piles transfer their load to the surrounding ground?

A
  • End bearing piles - transfer load through low bearing capacity soil to a strong stratum such as rock or very dense sand.
  • Friction piles - bear on frictional resistance between their outer surface and the soil in contact.
  • Settlement reducing piles - usually incorporated beneath the central part of a raft foundation in order to reduce differential settlement to an acceptable level.
  • Tension piles - resist uplifting forces that might otherwise cause the structure to be extracted from the ground due to uplifting forces such as hydrostatic pressure, seismic activity or overturning movement.
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10
Q

What is the difference between bored vs. pre-cast piles?

A
  • Bored piles are defined when the process for removing the spoil to form the hole for the pile is carried out by a boring technique.
  • They are used primarily in cohesive subsoils for the formation of friction piles and when forming pile foundations close to existing buildings where the allowable amount of noise and/or vibration is limited.
  • Pre-cast Concrete piles are generally used where soft soil deposits overlie firmer strata. These piles are usually driven using a drop or single action hammer.
  • Issues can arise due to the noise levels associated with the installation method of pre-cast piles.
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11
Q

What is a raft foundation

A
  • Raft foundations spread the load of the superstructure over a large base and reduce the load per m2 of the area.
  • Raft foundation solutions are useful in low bearing capacity soils.
  • They can be a solid raft slab or beam and slab raft such as a ground beam system and suspended PC concrete ground floor.
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12
Q

When would raft foundations be used?

A
  • A raft can be used for lightly loaded buildings on sites with poor soils.
  • Heavy loads to the raft have the potential to cause the raft to move sideways as a result of raft foundations not being very deep.
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13
Q

What is a strip foundation?

A
  • Strip foundations are formed by creating a shallow continuous excavation to support the perimeter and internal walls.
  • They are also referred to as strip footings and are suitable for most subsoils and a light structural design.
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14
Q

What are pad foundations?

A
  • Pad foundations provide a base for reinforced concrete or steel columns.
  • They are usually formed by making an isolated excavation in the shape of a square or rectangle.
  • They often have reinforcement mesh as part of the construction and spread the load to a layer of bearing soil or rock below.
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15
Q

What is powder coating?

A
  • A durable factory applied coating on metals, such as aluminum or galvanized steel which is available in many colours.
  • This application is sprayed on and is followed by heat curing to give a film thickness of 50 to 100 microns.
  • Any holes and cutting should be carried out before the coating is applied.
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16
Q

What is post tensioned concrete?

A
  • This method is usually employed where stressing is to be carried out on site after casting an insitu component or where a series of pre-cast concrete units are to be joined together to form the required member.
  • In post-tensioning, concrete is cast around ducts or sheathing in which the tendons are to be housed.
  • Stressing is carried out after the concrete has cured by means of hydraulic jacks operating from one of both ends of the member.
17
Q

What is the purpose of a threshold strip?

A
  • A lightly rounded metal strip over the joint between the floor finishes or coverings that meet under the door leaf.
  • They prevent fraying and provide an aesthetic finish which also interrupt combustible flooring under fire doors.
18
Q

What are the elements of a flat roof?

A
  • Joists which are fixed to wall plates to act as the main support.
  • Furrings which are fixed to the top of joists to provide the required gradient of incline.
  • Particle board is fixed to top of the furrings to provide a flat surface.
  • Felt is applied usually made up of 3 layers and bonded with bitumen to provide a waterproof covering.
  • Stone chippings provide protection to the felt and also reflect sunlight.
19
Q

What items would you expect to find on a timber or part glazed FD30 door?

A
  • 3 hinges.
  • Intumescent strip on door or edge of frame.
  • A self-closing devise.
  • If a glazing panel is present it must be 6mm thick, wired glass to a max of 1.2m2 with 13mm x 13mm wood beads encased with non-combustible materials.
20
Q

Explain how power is distributed to floor boxes in a raised access floor?

A
  • The incoming power supply connects to a low voltage switchboard, which in turn connects to a distribution board.
  • The distribution board will have an under floor busbar connected to it. The busbar has a number of sockets to which the floor box plugs into via a flexible lead. The floor box has sockets to which the appliances can plug into.