| What is concrete and its properties | It is rock-like material produced by mixing coarse aggregates (gravel or
crushed stone) and fine aggregates (e.g. sand), portland cement, and water. After curing, water evaporates and it shrinks slightly.
-Large compressive strength, little tension strength -> reinforcement with high tensile strength needed |
| What are the costs associated with concrete construction | -Formwork costs: labor, equipment, and materials (may make up to 60% total cost)
-Reinforcing steel and its placement
-Concrete materials, equipment, and labor for placing, curing, and finishing the concrete |
| Classify concrete into 3 types according to strength | Normal (20MPa to 35 MPa), High performance (55MPa), Ultra-high perofrmance (120MPa and above) |
| What is a slurry? | Slurry is freshly mixed concrete that is a semistable mixture od solids suspended in liquid |
| What is formwork used for and made out of | Used to shape concrete, made of braced wood panels, metal, or plastic |
| What is the theory of reinforced concrete | Theory of reinforced concrete: the reinforcing steel will be located at tensile
(stretching) regions in a structural member, and the concrete at the compression |
| Why are hooks used when making the steel frame for reinforced concrete | -Prevent buckling
-Prevent bond failure
-Resist seismic movement
-Prevent outward splitting or steel slippage
-Keep steel bars in position |
| Describe the process of pre-stressing reinforced concrete | 1. The steel strands are stretched across casting bed
2. Concrete is cast around the strands and bonds
3. When the strand is cut, the concrete is compressed inwards and takes on a camber (wide U shape) |
| Describe the process of post-stressing reinforced concrete | 1. Concrete is cast around the strand but not allowed to bond during curing
2. After concrete is cured, the strands are tnsioned and anchored to the ends of the beam |
