Disclaimer: This is rehashed from an article I wrote in August 2016 for GineersNow. Some parts are added or edited for clarity.
There are essentially two ways to manufacture concrete in any construction work: precast or cast-in-place.
Choosing between the two depends on the nature of the site work as well as application. But construction managers should lean towards using precast or prefabricated concrete over the other in most circumstances because of the following advantages:
- Precast concrete is manufactured in a controlled environment, hence it is much easier to control the quality of the mix, placement and curing.
- Using precast concrete instead of cast-in-place saves more time. Pouring concrete in-situ can add 3 days to the length of the project, while precast concrete can be made in advance and just be placed on site to be integrated in the structure. It can be installed immediately.
- There are no weather issues when it comes to precast. A fabrication site for precast concrete can operate regardless of the weather.
- Less labor is required in contrast to cast-in-place.
- For repeated, similar pieces like walls on a high-rise building, using precast is favorable because such products can be made out of one mold and one setup.
- Precast concrete can have accelerated curing, which increases strength gain; whereas cast-in-place concrete can have deviation in strength because of extreme temperatures and humidity.
- If there are last-minute changes in the design, precast concrete offers the flexibility to make such before the concrete is poured into the form.
However, there are limitations to precast concrete like the following:
- Due to the predetermined mold, architectural design can be limited. It is difficult to make adjustments for minor details unlike with cast-in-place concrete.
- To use precast concrete requires big initial investment particularly the molds or casts needed to fabricate concrete panels.