Construction tech & Environmental services Flashcards
Which RIBA Stage is on-site construction?
RIBA Stage 5 - Manufacturing and Construction.
What is buildability?
Buildability can be defined as the extent to which the design of a building facilitates the ease of construction.
To help improve buildability, early contractor involvement should be considered to benefit from their experience and expertise.
What are the benefits of off-site construction over in-situ?
Safety - Hazards such as falls from height are more likely to occur on site than in a factory.
Efficiency and quality - Construction takes place in a controlled environment.
Sustainability - Reduction in waste produced.
Speed - Work in the factory can be scheduled to begin at the same time as other activities on site, resulting in a shorter build programme.
What is the difference between building works and civil engineering works?
Building works: all types of buildings such as houses, offices, shops, hotels, hospitals etc.
Civil engineering works: drainage schemes, highways, culverts, bridges, retaining walls etc.
What are temporary works?
Temporary works are the parts of a construction project that are needed to enable the permanent works to be built, they are usually required for safety or access reasons. Examples:
Propping.
Scaffolding.
Formwork.
Excavation support.
What are hoists?
Designed for the vertical transportation of materials and/or people.
What is shoring?
Form of temporary support given to existing buildings and excavations. The purpose is to prevent collapse or excessive movement.
What is a culvert?
A culvert is a tunnel-like structure that is constructed to allow water to flow under a road, railway line or similar obstruction.
What is the purpose of a drainage headwall?
A headwall is a small retaining wall/structure built at the inlet or outfall of a storm water drainage pipe.
They are used to protect the end of the drain as well as protect the watercourse embankment from erosion.
What is the substructure of a building?
Substructure is the lower portion of the building (in the ground) which supports the superstructure.
Transmits the loads of the building to the ground.
Includes foundations, basements and retaining walls etc.
What is ground heave?
Ground heave is usually associated with clay soil which swells when wet, causing the upward movement of the ground.
As the soil generally cannot expand downwards or sideways, the result is that the exposed upper surface of the soil rises up.
What are some of the techniques available for ground improvement?
Vibro compaction.
Vibro stone columns.
Vertical drains and vacuum consolidation.
Soil mixing.
Dynamic compaction.
Dynamic replacement.
What are the different forms of excavation?
Site clearance operations (removing vegetation and rubble)
Stripping topsoil.
Reduced level dig (to reach formation level).
Cut and fill.
Excavation for foundations.
What are the key factors the contractor should consider when excavating?
Nature of the soil and moisture content of the ground.
Method of excavation.
If ground support systems are required.
Proximity of existing buildings.
Depth of excavation.
Underground services and drainage.
Can you explain some of the techniques to waterproof a basement?
Tanking - Materials such as asphalt, polythene sheeting, bitumen, etc. are applied internally or externally to provide a continuous membrane to the base slab and walls.
Drained Cavity - This method accepts a small amount of water seepage will occur. Cavity walls are formed, the water seepage is collected in the cavity and drained or pumped away.
Have you come across the term SUDS?
Sustainable Urban Drainage Systems.
SUDS are designed to manage stormwater locally (as close its source as possible), to mimic natural drainage and encourage its infiltration and/or attenuation.
SUDS help to reduce the reliance on existing drainage infrastructure.
Can you detail a typical road build up please?
Compacted and rolled type-1 subbase (100-250 mm).
Base course (70 - 150 mm).
Binder course (50 - 100 mm).
Wearing/surface course (20 - 40 mm).
What is the purpose of a foundation?
Foundations provide support for structures, transferring their load to the ground to avoid excessive settlement.
Foundations should bear the loads of the superstructure.
What are the typical considerations when selecting the type and size of foundations?
The total load of the building.
Nature and load bearing capacity of the ground.
Type of structure.
Cost.
Construction constraints (for example, their proximity to adjacent buildings/structures).
Soil conditions
What are the different types of foundation?
Strip foundations.
Pad foundations.
Raft foundations.
Piled foundations.
What is a raft foundation?
A raft foundation is essentially a continuous slab that extends over the entire footprint of the building. The raft spreads the load of the building over a larger area than other foundations, the stress acting on the ground below is reduced.
What are pad foundations?
Pad foundations are typically used to support individual or multiple columns, spreading the load to the ground below.
They are usually square or rectangular on plan and can be reinforced or non-reinforced.
What are strip foundations?
As the name suggests, the formation is in a strip of linear structure that ultimately serves to spread the weight across the total area of the ground, typically used to support masonry.
What are pile foundations?
A pile is a column (usually concrete) that extends deep into the ground.
Where the bearing capacity of the soil is poor or imposed loads are very heavy, pile foundations may be required.
There are two main types of pile:
End bearing piles.
Friction piles.
There are two main construction methods:
Bored piles.
Driven piles.
In what scenarios might a piled foundation be the best solution for the project?
Where the structure is heavy and the underlying soil is weak.
In areas where settlement issues are common.
Where the sub-soil water table is high.
Where the load distribution of the structure is not uniform.
Presence of horizontal forces.
Can you explain how end bearing and friction piles transfer the load of the building?
End bearing piles - The bottom of the pile rests on a layer of strong soil or rock, the load of the building is transferred through the pile onto the strong layer.
Friction piles - Friction piles work on a different principle, friction piles develop most of the pile-bearing capacity by shear stresses along the sides of the pile. In other words, the surface of the pile works to transfer the forces to the soil.
What are the differences between bored piles and driven piles?
The fundamental difference lies in their point of manufacture. A driven pile is formed off site under factory-controlled conditions and a bored pile is manufactured on site.
What are the key advantages and disadvantages of driven piles?
Advantages:
Piles can be precast to the required specifications.
Piles of any size, length and shape can be made in advance.
A pile driven into granular soil compacts the adjacent soil mass, the bearing capacity of the pile may increase as a result.
Fast, neat and clean installation.
Disadvantages:
Requires heavy equipment for handling and delivery.
Increased noise and vibrations generated by driving the piles.
Can be costly if piles are too short.
What are the key advantages and disadvantages of bored piles?
Advantages:
Any size or shape of pile can be formed on site.
No risk of damage during delivery and handling.
Reduced vibrations and noise.
Disadvantages:
Significant spoils are generated that need to be handled.
Reliance and coordination on multiple trades (reinforcement crew, piling crew and concrete supplier).
Unlike driven piles, bored piles do not improve the bearing capacity of the ground.
What are secant pile walls?
A wall is formed by installing interlocking piles which create a solid barrier free of gaps.
Typically used to form a retaining wall.
What is underpinning and why might it be required?
Underpinning is a method for repair and strengthening the foundations.
Stabilising foundations undergoing settlement.
Stabilising foundations that have moved because of landslip or unstable slopes.
Stabilising foundations affected by erosion, subsidence, or heave.
Stabilising foundations affected by vibration damage.
To increase the load capacity of the existing foundations.
To accommodate a new adjoining building, new basement, or deep sewer.
What is the superstructure of a building?
The structural components of a building constructed above the ground level (usually everything above damp-proof course).
The basic components of a building’s superstructure are columns, beams, slabs, walls etc.
What is the envelope of a building?
A building envelope is the boundary between the interior and exterior of a building.
The materials and components that form the external shell of a building such as brickwork, cladding, curtain walls etc.
What are the key considerations when designing external walls?
Weather protection.
Fire resistance.
Acoustic and thermal performance.
Structural performance.
Appearance/aesthetics.
Expected lifespan
Future maintenance.
Can you briefly explain what a retained fapade is?
The facade of the building is preserved whilst the rest of the structure is remodelled, or a new structure is built behind it.
Fagade retention is often used when restoring listed buildings.
What are standard brick dimensions in the UK?
Standard bricks are 215mm x 102.5mm x 65mm.
How many UK standard size bricks are required per m 2 ?
60 bricks per m 2 .
How many UK standard size blocks are required per m 2 ?
10 blocks per m 2 .
