Precast concrete is cast under controlled conditions at a factory which gives it outstanding versatility compared to traditional cast-in--situ concrete.
why precast concrete?
What exactly is concrete?
Concrete consists of three main components:
Cement - which acts as the binding component which "glues" all the solids together. The most common cement is Portland Cement.
Aggregates - the solid parts which are made up of fine and coarse components. Aggregate can come in the form of sand, natural gravel or crushed stone. At PCA we source our aggregates from recycled construction & demolition waste which has been screened, processed and crushed.
Concrete is referred to as a composite material because it is a mixture of multiple ingredients. The fine and coarse aggregates bond together with the cement and water to harden (cure) over time to create concrete.
What are the types of concrete - precast vs cast in situ
Precast concrete is cast and cured in a tightly controlled environment and then transported to its intended destination and put into place.
Cast-in-situ concrete is cast at the site of intended use which means the casting process is much more variable and can be dependent on weather, time and location.
What are the advantages of precast over cast in situ ?
Consistency - Casting conditions are more easily controlled because the casting is done in an environmentally controlled setting. Casting timelines are not dependent on the weather (we are able to pour our concrete in rain, hail or shine)
Ease - No excess preparation or equipment is required at the installation site
Reproducibility - Physical characteristics (such as tensile and compressive strength) can be measured and graded beforehand because of the ability to control most variables that go into casting the concrete
Versatility - being cast under controlled conditions means that a variety of shapes, finishes, colours and accessories can be included into the concrete block at the time of manufacture.
Modularity - blocks can be added or taken away from the structure relatively easily. This means the structure can be upsized or downsized as your needs change or even moved to another location!
What is MPa and how is it relevant to concrete?
MPa is a measure of the strength of concrete. Specifically it refers to the compressive strength of concrete - this is the amount of pressure a block of concrete can withstand from being crushed before it cracks, fails or crumbles.
One MPa is one million pascals. One pascal is one Newton of force per square meter. So one MPa is one million Newtons of force per square meter.
Our concrete is typically rated to 20MPa unless otherwise specified, which means our precast concrete blocks are rated to withstand a crushing force of up to 20 000 000 Newtons per square meter of force.
We have the ability to produce concrete which is stronger than 20MPa on request.