How Precast Concrete is Made
Precast concrete is considered as a construction product that is produced by concrete in a mold which is moved to be cured in a controlled environment. These structures are manufactured in a factory to be delivered to a job site. It is then ready for installation.
The usage of precast concrete is unlimited. It is used in various types of construction for multiple purposes from wastewater applications, building structures, communication and electrical utilities to bridges and more. Precast concrete gives extraordinary benefits such as providing high-quality, long life and durability.
How Precast Concrete in the US is Made
The process starts with setting requirements for precast components by a design engineer. With this, structural requirements for the area will be installed. The drafting team will then proceed to detailed drawings once the calculations are complete. The result will be submitted to the design engineer for approval.
Precast concrete is made up of admixtures, water, cement, fine and coarse aggregates. These are mixed in the factory’s batch plant based on the concrete mix design specified and provided by the engineer.
The concrete undergoes a variety of additional tests. This includes a spread test to verify the mix to have a proper flow without segregation of the aggregate. If approved, this will then be transported in a dispensing machine to the molds with the usage of an overhead crane.
As the crane is positioned over the mold, the team then fills each form with the required amount of concrete without trapping air voids. To avoid this, many plants use vibrating tables to completely settle. After the form is filled, the team levels off the top and specified finish are applied.
Curing the concrete process begins. The first step includes putting a tarp over the form overnight to capture the heat. This is the hydration process and capturing the heat generated will speed up curing. What helps the product to reach the full design strength? It’s the controlled environment of a precast factory that gives the product to properly cure.
Once reached, the stripping process begins. This is to remove the concrete from its form which includes a variety of steps such as opening the outer jacket, collapsing the inner core, and more. The product will then be moved to a finishing area.
The structure must be reviewed to ensure the final product meets the production drawings without visual defects. The final product must pass the QC inspection. If successful, the product is labeled awaiting delivery.