G-1 Concrete types, materials, additives and treatments Flashcards
Plain concrete
contained no reinforcing or steel mesh
Reinforced concrete.
concrete is ten times stronger at compression then tension. when concrete needs to resist high levels of torsion steel mesh or cares are imbedded within concrete.
Three fundamental properties that permit concrete to steel
- thermal expansion is equal
- cement paste in concrete bonds strongly to steel
- concrete protects the steel from rust
Thermal expansion
concrete and steel expand at the same rate when they are heated and shrink at the same rate when they are cooled.
Bonding
the bonding between cement paste and reinforcing steel transfers loads from one steel reenforcing bar to the next. the steel bars are overlapped usually 24x the width of the bar
Corrosion
during hydration the cement paste bonds with the steel that protects it from corroding. in underwater concrete steel gets covered with epoxy
Pre stressed concrete
this is when the reinforcing members in the concrete are placed in a state of permanent tension before service loads are applied.
two types of pre stressed concrete
Pre-tension
post tension
Pre tension Concrete reinforcement
high strength steel cables are placed into the formwork for the member and tensioned before the concrete is placed
Post tensioning concrete reinforcement
high strength steel cables are placed in formwork but not tensioned until after the concrete is placed.
Pre-cast Concrete
pre made concrete parts used for construction beams walls stairs floor slabs girders
Concrete shells
a shell is a long continuous beam of curved cross section which combines advantages os trusses, purlins and wind bracing through the interaction of its parts.
common shapes include barrels, domes, hyperbolic paraboloids and folded plates
Concrete masonry
concrete masonry is applied to pre cast block and brick building units moulded of concrete and used in masonry construction.
products are made of materials that comply with local building codes.
Concrete pipes
used for irrigation, drainage , sewer , culverts water supply
Concrete paving
concrete is leading paving material. designed for specific loads of traffic and cost less than other materials that can carry same load.
Air Entrainment
the use of air entrainment helps concrete to resist the damage caused by numerous freeze thaw cycles.
- air bubbles provide tiny chambers where water can expand into as it freezes.
Soil-Cement
Soil cement is a simply highly compacted mixture of soil, Portland cement, and water. as the cement hydrates the mixture becomes more durable.
- used for paving roads, streets, airports. to complete the pavement a thin layer of sealing is placed over it.
Shot- Crete (Gunnite)
this is portland cement that is applied by a pneumatically operated gun.
Grout
Portland cement grout is placed under pressure and is used for
- stabilizing foundations
- making rock foundations under dams water tight
- filling cracks in concrete work
Mortar
mixture of cement water and sand, bonds masonry materials together in a strong water tight bond
fibre Reinforced concrete
concrete that is reinforced with class or metal fibres. these are mixed with the concrete at the time of batching.
Self leveling gypsum
normally used on woodframe apartment buildings and condos. reduces noise and acts as a fire block.
Previous Concrete
concrete mix that is used for specific purposes. most of its uses at present are slab on ground.
similar to regular concrete made with cement, aggregats and water. different because finished product is porous
