Concrete
Concrete is massive and monolithic quality results from a mixture of Portland cement, water, and aggregate (usually made up of crushed stone or gravel and fine sand).
Precast concrete
Process
-Generally made at a factory before being moved to & installed at the site.
-The formwork in which precast concrete is cast is usually made of high-quality steel, coated plastic or wood and can be used many times, yielding a more consistent & controlled concrete member.
- Case and removed from form in 24 hour cycles with a high quality unit.
-When still freshly mixed, concrete can be manipulated to achieve a preferred texture, or objects can be cast into concrete.
Limitation
-Concrete can take any shape or form through casting. It can have a variety of surface textures, finishes and colours.
-Sculptural malleability.
-It is a shapeless material in which form, size & texture must be designed.
-Large elements cannot be precast.
-Design flexibility - using moulds to suit any requirement.
Usage
-Columns & beams, roof & floor slabs
-Cladding and paving, retaining wall
-Furniture
Environmental impact
-Precast concrete solutions leave a substantially smaller environmental footprint than other building construction methods
- Materials that use for precast concrete products come from natural and recycled sources; they are subject to minimal processing or chemical treatments to render them suitable for use, which results in concrete having a relatively low embodied energy value.
-Precast concrete is one of the solutions to lessen CO2. It has lighter structures, needed concrete strength is received with less cement than in cast-in-situ construction, concrete and thus cement waste is less are facts that decrease cement consumption/building m3 significantly.
-Less waste - lean production in manufacturing and exact elements are delivered to site
Advantages
-Low in cost.
-Fire proof construction material (it neither burns nor rots)
-Accelerate the construction process & can else be a time saving and cost effective method.
-Can be erected in poor weather conditions without having to wait for concrete to cure properly.
-More safety compare to case on site.
- Improved aesthetic - from grey off-form (made in steel casting beds) to a range of architectural finishes.
-Higher strengths - mean long life cycles, high loading capacities and long spans.
-Durable and low maintenance - up to 100 years service for high use applications.
-Energy efficient - high thermal mass reduces heating and cooling.
Disadvantages
-Concrete can fail if any component of its mixing, placement or curing is incorrect.
-Its weight and the complexities involved in the forming process.
-The concrete units can often be extremely heavy and large, making transportation to the construction site difficult.
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