Construction Tech and environmental Flashcards
You mention you have learned from other construction professionals, can you tell me an example of something you have learned this way?
- Project to carry make a large animal enclosure exhibit for a zoo in a large area of parkland.
- Architect and structural engineer designed a ha-ha ditch to creates a vertical barrier while preserving an uninterrupted view of the landscape beyond to the public so not so intrusive.
- The contractor excavated the walls of the HAHA to 45 degree angles to retain the soil and I arranged for a spray coating of grass to strengthen.
- Working with expert stonemasons on WA learned about Tottenhow Clunch stone.
Can you descirbe to me the following materials and their pros and cons? PICK TWO
- timber
- steel
- concrete
- stone
- glass
- gproc
Think:
- Uses?
- Installation time?
- Cost of materials
- Quality?
- Properties
- Acoustic/thermal insulator?
- Weather and decay resistant?
- Fire reistance?
- Strength?
- Flexibility and versatility before and once onsite
- Common defects
- deleterious?
- Sustainable and recyclable?
Timber
PROS
- Variety: Engineered glulam, cross laminated, softwood hardwood, fibreboard
- Sustainable and biodegradable
- Versatile- machined into all shapes, structural or decorative
- Cost - can be low
- Quality variable - natural product
CONS
- High moisture content – at 12% it is still dry
- Can decay
- Beetle attack common furniture beetle, death watch beetle
- Fungal attack - dry/wet rot
- Needs fireproofing
Glass
- TYPES
- Toughened, laminated plastic, double glazed with air or argon gaps
- PROS
- Decorative can be blown, stained
- Weather proof
- Transparent/ reflective.
- Cladding, facades
- Can be fire resistant pyroglass
- Good insulator when used with a gas filled interlayer
CONS
- Fragile, easily damaged- if layered strong
- Expensive and intensive to make heat to high temperatures
- Poor insulation value alone
- Can be subject to inclusions causing spontenaous breakage heat soak test.
- Not resistant to thermal or mechanical stress
Concrete
Made of Portland cement aggregate
PROS
- Strong in compression but not in tension so requires reinforcement or prestressing (pre-srtensioned and post tensioining) Compressive strength measured in C20 etc
- High performance admixtures available GRC, waterproof, accelterators
- Versatile – can be precast in moulds or cast insitu, liquid, sprayed
- Good fire resistance
- Good acoustic proerpties e.g. for resi flats
CONS
- Takes time to cure and strength check with cube samples, temperature affects this but can put additives in the mixture
- o Can be susceptible to chemical attack – alkali, sulphate, Cl
- Deleteriours material HAC Additives can cause degradation, also mundic.
- o Not weatherproof but can have waterproof additive
Steel
PRO
- Strong in tension
- Flexible without cracking
- Long spans are possible
CON
- Poor fire resistance alone needs fire protection
- Can corrode and expands on corroding (Regent’s Street Disease)
- Not flexible on site as prefabricated to size, if wrong size not much can do bolt on new section, use packers etc.
- Intensive production process (blast furnace, make iron first from iron ore, casting, forging etc)
Stone
PROS
- Natural product
- Can be highly decorative or purely functional
- Good fire resistance as non combustible
CONS
- Naturally porous can stain and also allow corrosion of steel regents street disease if suitable gap not left!
- Metamorphic, sedimentary, volcanic
- o May not be resistant to acid etc
- o Affected by weather
- o Slate roofing
Brick
Clay poured into moulds and fired in a kiln
PROS
- Lower moisture content
- Decorative
CONS
- o Subject to chemical attack
- Not strong alone
- weather resistance is variable - engineering bricks versus softer decorative which can erode.
Gyproc
Plaster, can be used wet as a mix or made into preformed sheets with insulation backers for partition walls.
PROS
- Good for finishes
- Can be fire resistant
CONS
- Not moisture resistant
Can you describe the floor build up in an industrial building
Compacted hardcore, Poured concrete reinforcement, DPM, floateds screed.
can you describe floor build ups in a commerial high building?
- Hollow pot
- Filler joist
- Waffle slab
- Steel composite deck - holorib?
What types of floor might you see in a residential premises
- suspended timber
- beam and block
- concrete screeded
What sort of floors might you see in an office block?
- Coffered floors or waffle slab is common in a 1960s office block - precast units with steel reinformcement and precast columns. Longer spans and services run under floors
- Filler joist (vacuum injection resin repair)
- Hollow pot
- Steel composite deck - like holorib.
- Precast concrete units (like beam and block!) Pre stressed units e.g. pre or post tensioned floors The use of post-tensioned reinforcement to construct floor slabs can result in thinner concrete sections and/or longer spans between supports - tendons pulled tight once onsite.
What is Radon and how might you remedy it?
Contaminated ground and radon
Radon is a naturally occurring gas which is found in certain areas of the country. These gases need to be ventilated and a gas membrane will be required to stop them from entering the building.
Can you tell me what periods of buildings you know of and types or architcture prevalent at the time
1960/70s brutalist concrete
Post War 1945-1955 prefab
1920s First world War Art Deco
Edwardian: 1901–1914
Victorian: 1837–1901 Gothic, queen anne mock tudor
Georgian: 1714–1837 palladian, italian (neoclassical)
Elizabethan: 1558–1603 half timbered - warwickshir
Tudor 1485–1603 half timbered
What can you tell me about modern methods of construction
- It centres around the use of off-site construction techniques that can benefit from factory conditions and mass production techniques. - lean construction
- Not new - schools have been using mobiles for years and post war there was an influx of prefab housing due to housing shortages, not always the best quality and often problems now insuring non standard construction
- 2017 The NHBC launched an online MMC hub to help inform house-builders about modern methods of construction.
- Pods - bathrooms craned onto site and integrated to the structure
- Fast food restarurants and budget supermarkets prefab panelling systems - quick installation and cheap to build.
- Cross laminated timber - structural uses consider fire. it is engineered wood panel product made from gluing together layers of solid-sawn lumber, i.e., lumber cut from a single log. Sustainable, good insulation, timber can be suceptible to rot (i have dealt with a glulam canopy structure which was rotte through, admittefly gluam has less strength that cross lamiated. The tube sculpture chelsea london design festival
What is post war prefab?
- Tin town in luton british steel BISF British Iron and Steel Federation, houses steel tublar structure different cladding betwen upper an dlower floors often upper had profile sheet cladding. these were designed as permanent and should be mortgageable.
- Many prefab houses consist of precast conrete panels which were subject to concrete cancer (akali silica reaction)
What is a honey comb sleeper wall?
- A sleeper wall is a short wall used to support floor joists, beam and block or hollowcore slabs at ground floor.
- They have holes between bricks to allow constant air circulation.
- It is constructed in this fashion when a suspended floor/slab is required due to bearing conditions or ground water presence.
What is meant by a waffle slab, how is it constructed and why?
- Waffle slab is a concrete floor slab so called because the soffit resembles a waffles due to the deep sides square grid with coffers resembling a waffle shape,
- It was common in the 1960s in multi storey buildings including offices and concrete car parks.
- it was often used where large spans are required without the interference of columns.
- It can support greater loads than conventional slabs.
What other types of concrete slab do you know of?
- hollow core - precast units longitduinal voids and reinforcment - preformed service ducts, longer spans.
- solid raft foundation - reinforced solid often foudnations poured in situ.
- Composite slab - profile steel deck
- Waffle slab - longer spans, less crossectional area.
