Temporary Structures and Concrete Containment
The skeleton and the skin. Learn how much wood and steel it takes to hold tons of wet concrete against gravity and pressure.
Formwork (Shuttering)
Formwork is the "mold" into which wet concrete is poured. It must be strong enough to withstand the **Hydrostatic Pressure** of liquid concrete and the vibration of the casting process. The most common material today is BWP Plywood (Boiling Water Proof) or steel plates. The "Contact Area" is the total surface where the plywood physically touches the concrete.
Standard Contact Area Formula
Scaffolding (Staging)
Scaffolding is the structural support system (Prop-work) that holds the formwork in place.
1. Cuplock System: Fast to assemble, used for heavy slabs.
2. H-Frame: Standard for vertical wall support.
A typical rule of thumb for staging is roughly $2.5$ meters of pipe per cubic meter of space supported.
Repetition and Repurposing
One of the biggest cost-saving factors in construction is the Repetition Rate. Good quality plywood can be reused $5$ to $10$ times. If your project has $20$ floors, you don't buy plywood for $20$ floors—you buy it for $2$-$3$ levels and "recycle" it as you move upward. Proper use of **Shuttering Oil** (Release Agent) is critical to prevent the plywood from bonding to the concrete, which ruins both the finish and the wood.
Frequently Asked Questions (FAQ)
When do I remove the formwork ('Deshuttering')?
It depends on the cement type and temperature.
- Vertical sides (Columns/Walls): 16-24 hours.
- Slab soffit (props left): 3 days.
- Beam soffit (props left): 7 days.
Removing forms too early can lead to structural sagging or even total collapse.