Concrete Introduction Flashcards
What’s concrete used for ?
High and low rise buildings, long span bridges, tunnels and pipelines, and pavements.
Why is concrete used ?
Constituents widely available, low technology system, strong and stuff in compression, compressive strength to price ratio is high, high Young’s Modulus for cost per unit volume, high compressive strength compared to tensile.
Concrete can be reinforced with steel or not reinforced at all. What are the different ways of preparing concrete ?
Plain concrete can have no reinforcing bars such as pavement slabs or dams.
Reinforced concrete - includes reinforcing bars.
Pre-stressed concrete has reinforced bars which are tensioned. Pre-tensioned are done before casting and post-tensioned after. Counteracts load stresses.
What is concrete reinforced with?
Steel and propylene can reinforce concrete.
What does fibre reinforcement do?
Increases structural integrity, reduces permeability and bleeding of water, increases impact, abrasion and shagger resistance, provides strength against tensile forces.
What are nice properties of concrete for shaping ?
Concrete is flexible and can be shaped nicely, can make intricate structures and large structures with few joints
What environments can concrete survive in?
Concrete can survive in heat including fire, wet and dry environments, industrial and chemical environments, radioactive and electro-magnetic environments and seismic.
How does steel reinforcement fixing in steel construction?
Steel reinforcement fixing involves fastening steel reinforcement bars to keep concrete in place. Puts concrete in strain to resist loads.
How does precasting work?
Concrete is often precast with components cast in a factory, hardened, then transported and installed.
How does pouring in situ work?
Concrete can be poured in situ, with concrete cast in its final position.
How does compaction work?
Compaction by poker vibrator works by shaking concrete after pouring to remove air bubbles to improve strength. This can be done by vibrating beam too or formwork vibrators.
How are columns cast ?
Concrete columns are cast in formwork which is then removed after concrete has set.
What finishing techniques are used?
Finishing produces a dense flat surface. Power floats can be used to finish surfaces or a magnesium float. Bull floats are flat long handled tools to flatten surfaces.
What is curing ?
Curing is maintenance of a suitable environment through moisture and temperature at the surface of concrete.
What are energy benefits of concrete ?
Low production energy and low energy in use
