Corrosion and Rust to Permanent Steel Formwork (Bondek, Condeck, etc.)

Permanent steel formwork (generally known as “Bondek” or “Condeck” in Australia) is commonly employed to construct suspended slabs in both residential and commercial structures. The permanent steel formwork can provide some economic benefit at the time of construction by reducing the volume of propping and eliminating the need for contractors to remove formwork after construction.

Although this steel sheeting is a means of formwork it is also regularly acting as a bottom layer of reinforcement within the slab, therefore making it an integral part of the suspended structure. Consequently, if the condition of this steel sheeting has too deteriorated the suspended slab can fail or collapse. Significant engineering investigations including concrete scans (GPR / X-ray) or destructive testing is generally required to confirm the construction details of the slab and to assess if the steel sheeting is just formwork or an integral part of the slab. We recommend a suitably qualified engineer always be contacted to investigate your specific slab.

Rectification of the rusting steel formwork can be as simple as removing surface rust and treating sections with appropriate rust treatment products, or where rusting is severe and has been allowed to spread throughout the structure, complete demolition and replacement of sections may be required. Early intervention and rectification can be the difference between simple repairs or complete demolition. A suitably qualified engineer will have to be contacted to consider the specific suspended slab’s construction, location, and possibly service conditions to determine an appropriate rectification procedure.

We recommend you contact Booth Engineers and Associates Pty Ltd to evaluate your rusting steel formwork today.