Understanding the Concrete Formwork Process: Omni Wedges, Form Ties, and Turnbuckles
Concrete formwork is one of the most critical stages in construction. Before concrete can be poured, a temporary structure must be built to hold the wet concrete in the desired shape until it gains sufficient strength. Behind every successful concrete wall is a system of forms, ties, wedges, washers, and alignment hardware working together.
What Is Formwork?
Formwork is a temporary mold, usually made from plywood, steel, aluminum, or composite panels, used to shape concrete structures such as walls, columns, foundations, and slabs.
The formwork system must:
Maintain the desired wall dimensions.
Resist the pressure of wet concrete.
Remain properly aligned during the pour.
Be easy to strip and reuse.
Key Components of a Wall Form System
Form Panels
The form panels create the actual mold for the concrete. These are often made from plywood attached to a steel or aluminum frame.
- Form Ties:
Form ties connect the two sides of a wall form together and prevent the forms from spreading apart under concrete pressure. - Washers and Waler Plates:
Washers play a crucial role in distributing load across the formwork system.
Common purposes include:
Spreading pressure over a larger surface area.
Preventing hardware from pulling through plywood.
Supporting tie rods and alignment components.
Providing a secure bearing surface for wedges and clamps.
Without washers or bearing plates, concentrated loads could damage the form panels and compromise the integrity of the formwork. - Omni Wedges:
Omni wedges are reusable steel locking devices used to secure form ties and waler systems.
Their function is simple but essential:
The form tie passes through the wall forms.
A washer or bearing plate is positioned against the form.
The Omni wedge slides into place.
The wedge is hammered tight to lock the assembly.
This creates a strong connection capable of resisting the lateral pressure generated by freshly poured concrete.
Turnbuckles: The Alignment System
The hardware shown in the photo below is a formwork turnbuckle. - A turnbuckle is used to:
Plumb wall forms vertically.
Adjust alignment before concrete placement.
Brace form panels against movement.
Fine-tune wall positioning.
The threaded mechanism allows workers to lengthen or shorten the brace with precision.
How It Works
One end attaches to the form panel or strongback.
The other end anchors to the ground or a brace point.
Rotating the center adjustment section changes the length.
Workers use the adjustment to make the wall perfectly plumb.
This process is repeated until all wall forms are aligned according to design specifications.
Typical Formwork Installation Process
Step 1: Layout
Surveyors and carpenters mark wall locations and elevations.
Step 2: Install First Form Side
The first side of the wall forms is erected and temporarily braced.
Step 3: Install Form Ties
Form ties are installed through predetermined tie locations.
Step 4: Install Washers and Omni Wedges
Washers, bearing plates, and Omni wedges are installed to secure the form ties.
Step 5: Install Turnbuckles
Turnbuckles and braces are attached to align the wall.
Step 6: Plumb and Square
Workers adjust turnbuckles until the forms are:
Level
Straight
Square
Plumb
Step 7: Concrete Placement
Concrete is poured carefully while workers monitor the forms for movement.
Step 8: Stripping
After the concrete reaches the required strength:
Omni wedges are removed.
Form ties are released.
Forms are stripped.
Hardware is cleaned and reused.
Why These Small Components Matter
While plywood panels are the most visible part of formwork, the system relies heavily on hardware such as:
– Washers
– Waler plates
– Omni wedges
– Form ties
– Turnbuckles
– Strongbacks
Each component plays a specific role in resisting the tremendous forces created during a concrete pour. A properly assembled formwork system ensures safety, accuracy, and a high-quality concrete finish.
Final Thoughts
Formwork is much more than temporary molds—it is a precisely engineered system. Components like Omni wedges lock the forms together, washers distribute loads safely, and turnbuckles ensure walls remain perfectly aligned. Together, these elements create the foundation for strong, accurate, and durable concrete structures.
For construction professionals, understanding how each piece of hardware contributes to the overall system is essential for both safety and efficiency on the job site.