Contractors are challenged with placing new, solid structures up against existing concrete walls or other difficult materials that divide property lines. There are two options for them: blind sided or single-sided forms. A blindsided wall system uses specialty devices or two-sided forms to fill the space between the old wall and new wall. Single-sided forms are different in that they require conventional form ties that resist concrete pressure.
When developing a single-sided form, even the slightest oversight can lead to a bulge, blowout, or out-of-tolerance walls. Here are five common causes for single-sided form failures.
Exceeding Design or Working Pressure
Pouring procedures should abide by best practices, but more importantly, they must be compliant with governmental regulations, codes, and ordinances. Neglecting to do so can result in over pouring, misconstruing mix design, implementing improper vibration, or overlooking temperature.
Improper Use of Ties
If ties are not properly placed or fastened, the single-sided form is not adequately supported. Be careful not to weld, bend, or alter wall ties as it may weaken them. Check the manufacturer’s recommendations to ensure all connectors are in the right position.
The manufacturer should provide approved layouts, but if not, a trained formwork designer should prepare them. If you have the manufacturer’s layouts, carefully follow their recommendations for installation and anchoring devices; otherwise, you’ll face setbacks in your timeline.
Job-built fillers, corners, and bulkheads are the cornerstone for a strong foundation. When field personnel erroneously design them, they become the weakest link of the entire structure. A qualified designer should design them specifically to combat concrete pressure.
When personnel don’t brace at least one side of the formwork or don’t install appropriate connecting hardware, you can expect a single-sided form failure. Use concrete-resistant braces calculated by a designer, and do not exceed the rated load of braces. Rely on personnel with sufficient experience and knowledge inspect the anchorage of braces for stability.
Lack of Inspection
It is vital that qualified personnel assess how the form layout has been interpreted and executed. Prior to pouring concrete, assure that the ties are in the right place and all correlating hardware is secure. Confirm that proper thread engagement is intact for connectors like ties, inserts, and anchor bolts. In addition, before and during the concrete pour, the contractor needs to inspect the formwork design so as not to exceed the required rate of pour or overload the formwork.
Call the Experts
If you’re worried about single-sided form failures, Forming America is here to help. We’re a concrete forming and shoring equipment company, and we sell, rent, and renovate formwork. Our specialty is Symons Steel-Ply forms and accessories, but we also handle other types and brands of equipment. Contact Forming America or call 1-888-993-1304 today to outfit the next project for your company.