Concrete Formwork Failure : Common Causes and Remedies

There are lots of incidents where concrete formwork failure occurs during and after concrete placement. Formwork failure leads to concrete blowouts, collapse of formwork components or structural collapse, delay in construction, rise of construction cost as well as death or serious injury.

Causes of formwork failures - Formwork failures occur due to the following reasons:

• The design of formwork is made by a incompetent person
• The formwork is not arranged compliant with the formwork design or specifications
• Onsite alterations to formwork caused by site conditions is not considered in the design
• Application of damaged or inferior formwork components
• Elimination of formwork prior to concrete attains ample strength
• Overloading of the formwork throughout the concrete pouring operations.
• Omissions in the assembly detail
• Workmanship fault owing to rapidity, indifference, or scarcity of knowledge
• Heavy rain that leads to falsework foundation slippage
• Failure of equipment for moving formwork
• Concentrated load caused by imperfect prestressing operation
• Concentrated load owing to construction material
• Impact loads from concrete debris
• Insufficient falsework cross-bracing/lacing
• Insufficient number of shoring
• Inadequate soil foundation
• Lack of inspection of falsework/formwork throughout the concreting

To resist the formwork failure, perfect prevention strategies should be undertaken. Good practice in designing, constructing, and handling formwork will maintain protection as well as efficiency and economy.

Safe Work Method Statement: Safe work method statements (SWMS) should be properly formed for all high risk construction work that is the significant part of the formwork erection, concrete pouring and formwork stripping methods.

SWMS facilitate the employers and employees to detect the hazards and risks related to the high risk construction work as well as opt for useful control measures.

Also Read: Variations among formwork, shuttering, centering, staging and scaffolding

Formwork Safety: Erecting formwork -

1. Make sure that a competent person makes the formwork design to sustain the probable dynamic and static loads.
2. In case the proprietary formwork systems are used, they should be constructed according to the manufacturer’s recommendations.
3. In case a custom design is applied, including while integrating various formwork systems or employing the proprietary systems outside the manufacturer’s recommendations, make sure the design is created by an engineer having expertize in formwork design.
4. The formwork components should be examined properly prior to be used, take away faulty components from service and tag them out for disposition or repair.

5. Prior to other trades obtain the formwork or the concrete is poured, a skilled person should be employed to examine that the erected formwork erected compliant with the formwork design. The skilled person should record the inspection and sign-off the formwork as ready for use.
6. If the erected formwork does not conform to the formwork design:

a. Modity the formwork so it adheres to the design, or
b. Make sure the designer examines the formwork and validates that the structural integrity of the formwork remains unchanged.

Pouring concrete:

• The structural integrity of the formwork should be examined prior to provide the concrete pour.
• Build up a proper exclusion zone so that the people can't enter to the area under the formwork throughout the concrete pour and preserve the zone unless the concrete attains adequate strength.
• Check the formwork throughout the concrete pour to recognize any preliminary failure. The monitors should not enter the areas under the formwork until a risk assessment is made to establish it is safe to do so.
• Verify the formwork is not overloaded throughout the concrete pouring operation.

Stripping Formwork: Prior to eliminate the formwork, the concrete should attain minimum strength. It can be obtained by maintaining the minimum curing time stated in the formwork design as well as getting the proper following concrete sample testing.