Construction Technology Flashcards
What 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
What are the benefits of off-site construction over in-situ construction?
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 engineer works?
Building works: all types of buildings such as houses, offices, shops, hotels.
Civil engineering works: drainage schemes, highways, culverts, bridges.
What is the substructure of a building?
Substructure is the lower portion of the building (in the ground) which supports the superstructure. It transmits the loads of the building to the ground.
What are some of the techniques available for ground improvement?
Vibro compaction, Soil mixing, Dynamic compaction.
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.
What are the different forms of excavation?
Site clearance, Stripping topsoil, Cut and Fill, Excavation for foundations.
What are the key factors the contractor should consider when excavating?
Nature of the soil and the moisture of the ground, method of excavation, proximity of existing buildings, depth of excavation, underground services and drainage.
Can you explain some of the techniques for waterproofing a basement?
Tanking – materials such as asphalt and bitumen are applied internally or externally to provide a continuous membrane to the base slab and walls.
Drained cavity – This method accepts that a small amount of water seepage will occur. Cavity walls are formed, and the water seepage is collected in the cavity and drained or pumped away.
What are SUDS?
Sustainable Urban Drainage System. They are designed to manage stormwater locally and mimic natural drainage to encourage its infiltration. Can help reduce the reliance on existing drainage infrastructure.
Give some examples of a SUDS?
Green roofs, Detention Basin, Wetlands.
Can you detail a typical road build-up?
Compacted and rolled type-1 subbase (100-250mm)
Base course (70-150mm)
Binder course (50-100mm)
Wearing/surface course (20-40mm)
What are the two main types of roads/pavements?
Rigid and Flexible
What are the characteristics of flexible pavements?
Bitumen and asphalt aggregates are typically used. The structure of the pavements is designed to bend and deflect according to external factors like traffic loads and weather.
What are the advantages of flexible pavements?
Can be applied during the pre-construction phase, repairs are easy and can be opened and patched, materials are inexpensive, short curation time means short traffic and business disruptions.
What are the disadvantages of flexible road/pavements?
Shorter lifespan than rigid pavements, frequent maintenance required which drives up cost.
What are the characteristics of rigid pavements?
Typically made out of cement concrete with a base and sub base. Unlike flexible pavements, rigid pavements do not bend under pressure. Top layer of concrete absorbs most of the pressure and weight from traffic.
What are the advantages of rigid pavements?
Longer lifespan, maintenance costs are low, allows for future asphalt resurfacing, allows for wider load distribution with fewer base and sub base requirements, can be installed on low and high quality soils
What are the disadvantages of rigid pavements?
Initial installation fee is expensive, costs of repairs is expensive. Low and very rough riding quality.
What is the purpose of a foundation?
Foundations provide support for structures, transferring their load to the ground to avoid excessive settlement. The 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, load bearing capacity of the ground, type of structure, cost.
What is a raft foundation?
A raft foundation is 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, reducing the stress acting on the ground below.
What are the different foundation types?
Pad, Strip, Pile, Raft
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 and can be reinforced.
What are strip foundations?
Strip foundations are a strip of linear structure that serves to spread the weight across the total area of the ground and is typically used to support masonry.
What are pile foundations?
Pile foundations are columns that extend deep into the ground. Where the bearing capacity of soil is poor or imposed loads are very heavy, pile foundations may be required.
What are the two main types of piles?
End bearing piles. Friction piles.
What are the 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 water table is high. Where the load distribution of the structure is not uniform.
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 side of the pile. In other words, the surface of the pile looks to transfer the forces to the soil.
What are the differences between bored and driven piles?
A driven pile is formed off site under factory-controlled conditions and a bored pile is cast on site.
What are the key advantages and disadvantages of driven piles?
Pile can be precast to the required specifications. Piles can be of any size, length, and shape and can be made in advance. A pile driven into granular soil compacts the adjacent soil mass and therefore can result in the bearing capacity of the pile increasing as a result. Fast, neat, and clean installation.
What are the disadvantages of driven piles?
Requires heavy equipment for handling and delivery. Increased noise and vibrations generated by driving the piles. It can be costly if the piles are too short.
What are the key advantages of bored piles?
Any size or shape of pile can be formed on site. No risk of damage during delivery and handling. Reduced vibrations and noise.
What are the key disadvantages of bored piles?
Significant spoils are generated that need to be handled. Reliance and coordination on multiple trades. Unlike driven piles, bored piles do not improve the bearing capacity of the ground.
What are secant pile walls?
A wall formed by installing interlocking piles which create a solid barrier free of gaps. Typically used for a retaining wall.
What is underpinning?
Underpinning is a method for repairing and strengthening existing foundations.
Why might underpinning be required?
Stabilising foundations undergoing settlement, foundations moved due to landslide. To increase the load capacity of existing foundations. To accommodate a new adjoining building, new basement etc.
What is the superstructure of a building?
The structural components of a building which are constructed above the damp-proof course. The basic components include a building’s superstructure are columns, beams, slabs, walls, roof, floors.
What is the envelope of a building?
A building envelope is the boundary between the interior and exterior of a building.
What are key considerations when designing external walls?
Weather protection, fire resistance, acoustic and thermal performance, structural performance, appearance/aesthetic.
Can you briefly explain what a retained façade is?
The façade of the building is preserved while the rest of the structure is re-modelled, or a new structure is built behind it. It is often used when restoring listed buildings.
What are standard brick dimensions in the UK?
215mm x 102.5mm x 65mm
How many UK standard bricks are required per m2.
60 bricks per m2.