Formwork – the building blocks for concrete structures
Posted 24 May 2024 by The SEL Team
Concrete construction is a fundamental component of our built environment and the various shapes and sizes that concrete structures can be moulded into cannot happen without formwork.
What is Formwork?
Formwork is a temporary structure used to contain wet concrete to mould it to the dimensions required and to provide temporary support until the concrete structure can support itself. Traditionally, timber shuttering was used for temporary support in concrete works, and although the use of timber is still a proven method, modern technology and techniques have improved formwork in many ways – making life easier when it comes to building concrete structures.
Considerations for Formwork
The following considerations need to be taken into account when deciding on formwork:
Formwork need to be strong enough to withstand load – these are forces that can cause stresses, displacement and deformations on a building. Loads the formwork is designed to take include pressure from wet concrete, access loads from access platforms and/or working platforms attached to the formwork and wind loading.
Formwork need to be capable of holding its shape by being efficiently propped and braced horizontally and vertically, it needs to be designed to prevent leakage of cement and needs to be able to be removed in various parts without causing damage to the concrete.
It’s important for Formwork to be resting on a firm base and accurately set to the desired line. In addition, good formwork should be as lightweight as possible, be resistant to warping and distortion and suitable for re-use.
Types of Formwork
According to The Concrete Centre, the main types of formwork used in modern construction include the following:
- System column formwork
- Horizontal panel
- Slipform
- Jumpform (also known as Climbing Formwork)
- Vertical panel systems
- Permanent formwork used in some types of hybrid concrete construction.
At Site Equipment Ltd (SEL) the preferred formwork system is the Frami Panel System and Slimshore Soldiers.
What is Frami and Slimshore?
Frami Panel System is a modular system used for quickly forming many types of layouts and is ideal for fast and economical forms with or without a crane. Made from galvanised steel, it is lightweight, flexible system that is easy to assemble (only needs two people) and unlike timber shuttering that can only be reused a few times and is time consuming to set up, Frami Panels can be reused time and again, thus reducing the level of waste on site. It is versatile in that it can be used for single- or double-sided formwork and an efficient means to form walls, foundations and columns.
It is versatile in that it can be used for single- or double-sided formwork and an efficient means to form walls, foundations and columns.
Slimshore Soldiers is a modular propping system and often used alongside Frami Panels to support single-sided formwork. Easy to transport and assemble, Slimshore offers incredible strength to weight ratio and with the range of accessories available from Site Equipment Ltd (SEL), this system can be deployed in various settings for a number of uses, including HD Push-Pull Props, HD Props and Needling.
Temporary Support Systems Built for Efficiency
Working efficiently is important in any construction programme and therefore formwork systems like Frami and Slimshore can really deliver. Here’s why:
Frami System is easy to assemble
Frami can be assembled quickly for use on a variety of construction jobs. Frami panels can be pulled together to achieve a correctly aligned panel joint that is resistant to tensile forces. The continuous hardware slot in the frame means that the Frami clamp can be fixed anywhere on the frame – making it possible for panels to be continuously height mismatched with no need for a pre-defined grid. This means that the formwork can easily accommodate a variety of jobs, such as slopes, steps, slopes and uneven ground.
Frami System is re-usable
The long lifespan of Frami Panels is another added benefit, especially as more contractors look to improve efficiencies and opportunities to re-use, reduce and recycle. Frami panels can deliver high numbers of re-use cycles whilst still delivering good concreting results, unlike traditional timber shuttering that can only be used up to 10 times or can become unusable if, for example, timbers absorb moisture. Frami panels use special timber-plastic composite sheets, which are easier to clean and the surface structure of Frami also prevents splintering and swelling caused by nail-holes, ensuring that concrete work has a perfect finish.
Frami panels from Site Equipment Ltd (SEL) can provide a safe Working Load of 50kN/m² and doesn’t require a crane to move. Straight or curved panels are available of up to 3,000mm high.
Slimshore Soldiers provide strong temporary support
Slimshore Soldiers are robust and manufactured from high-yield steel, therefore combining durability and load capacity. This modular system is well-known for its use in Needling and Propping; however, it can also be used in formwork and other temporary works such as:
- wall formwork
- vertical and raking shores
- spanning beams and trusses
- façade retention
- bridge cantilever edge and deck supports
- safety screens for use in hi-rise construction.
Site Equipment Ltd (SEL) can supply Slimshore Soldiers in eight sizes.
Equipment safety
All our equipment is regularly checked by the experienced staff at Site Equipment Ltd (SEL), meets the relevant health and safety standards and is complete with test certificates where applicable.
Temporary Works Design for Formwork
For more complicated jobs, such as Formwork, Temporary Works Design can be provided by Site Equipment Ltd (SEL).
Temporary Works Design is an engineered solution and has several advantages if you have a complex project – the most important being that it provides assurance to the safety and buildability of a solution used on site. Often, designs are required to satisfy Health and Safety requirements, but can also be instrumental in a Contractor’s Method Statement and Risk Assessment (RAMS) – generally giving the Contractor the confidence to do the job. Through Temporary Works Design, risks can be ‘designed-out’ of the job to complete it successfully and safely and this can be done before using Frami Panels.
Engineer’s considerations for Formwork
According to Engineers Daily, designing and building formwork requires a basic understanding of the way in which concrete behaves. Key considerations for Formwork when it comes to Temporary Works Design may also include:
- Height of concrete pour
- Concrete pour rate
- Weight of concrete
- Temperature
- Type of cement and cement substitutes such as CCGS or PFA Admixtures, retarders and plasticisers
- Vibration
- Concrete slump (water–cement ratio)
- Chemical additives
Formwork drawings will be supplied by the Engineer doing the Temporary Works Design and should include details of the following:
- formwork and formwork joints
- access platforms
- pour sequencing
- ties
- size and spacing of framing
- details of proprietary fittings or systems proposed to be used, and bond breakers, if used.
Site Equipment Ltd (SEL) will provide all the drawings and calculations to the Contractor’s appointed Temporary Works Design Coordinator (TWC), who will be responsible for executing the job correctly and safely. Where a number of subcontractors are involved, it may be appropriate for one or more Temporary Works Supervisors (TWS) to be appointed, who should be responsible to the TWC in the supervision of temporary works.
Standards Matter.
Our Engineers will be able to deliver Temporary Works Design for Frami and Slimshore and work according to the BS5975 UK standard for Temporary Works Procedures and Design.
The BS 5975 Standard provides recommendations and guidance on the procedural controls to be applied to all aspects of temporary works in the construction industry; it also gives recommendations and guidance on the design, specification, construction, use, and dismantling of falsework.
Safety considerations for installing Formwork
It is the Contractor’s responsibility to ensure the health and safety of workers on site during formwork installation. Due care and attention need to be taken during site preparation to avoid trips, slips and falls – making sure workers are aware of uneven surfaces, obstacles, trailing cables are tied down, wet and slippery surfaces are treated and ramps and/or signage are used when there are changes in level at, for example, doorways.
How to hire Frami and Slimshore or book Temporary Works Design
To order Frami and/or Slimshore Soldiers for formwork and to get advice about the engineered solutions provided by SEL contact the nearest SEL depot or call us on 0117 982 8236.
