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Formwork release agents

Understanding the crucial role formwork plays in the production of quality concrete and moulds in the manufacture of precast elements, the Chryso® DEM range has introduced much-needed flexibility to the industry. Previously, it had been a case of one-size-fits-all when it came to release agents.

Aesthetics of the finish

Discerning clients, developers, manufacturers and specifiers are increasingly particular about the aesthetics of concrete finishes. To achieve the desired texture and colour finish on the concrete’s surface, it is imperative that formwork surfaces are adequately prepared in terms of cleanliness and that an optimal release agent is selected for the application.

As different form-face materials have varying longevity, absorbency and texture characteristics, specialised release agents are required to realise the full aesthetic potential of the formwork, eliminating wastage of time and materials.

Not only will the optimal release agent reduce the likelihood of imperfections and surface defects (particularly blow holes) in the concrete, but – if applied correctly – it will ensure that there is no staining or deviation from the specified colour finish.

Precast plants

The top-quality release agents in the Chryso® DEM range provide greater coverage, are easy to use and add consistent quality, which is important on construction sites, as well as in precast plants.

Chryso® DEM Bio 10 is a vegetablebased, biodegradable and non-toxic release agent which will not pollute the environment. It has a low odour and is therefore safe to use in confined spaces such as mining, tunnelling and any poorly ventilated areas. It is suitable for use with all types of formwork: metal, wood, plastic, polystyrene and fibreglass.

Another product in the range is Elio “The top-quality release agents in the Chryso® DEM range provide greater coverage, are easy to use and add consistent quality, which is important on construction sites, as well as in precast plants.”

(Top, left and above): Specialised release agents are required to realise the full aesthetic potential of the formwork.

VP, a hydrocarbon oil-based agent, which is suitable when producing concrete pipes with roller-compacted pipe technology. The Elio VP significantly reduces surface defects. The low viscosity oil creates less surface tension against the sides of the pipe steel moulds, resulting in less outer concrete surface damage when demoulding.

Chryso® DEM Oleo WB is a waxbased delayed-release agent for wooden formwork used on conventional jobsites and for wooden pallets for cement-based brick manufacturing. This release agent temporarily protects and extends the life of veneer-laminated shutter boards, decreasing the frequency of re-lamination. It can also be used to coat pallets for protection, when stacking cement-based bricks on them.

Chryso® DEM Oleo FW is hydrocarbon-based, making it suitable for use with all types of formwork. However, it is not suitable for precast applications. It ensures ease of formwork release and also temporarily protects and extends the life of metallic formwork from corrosion.

Chryso® DEM Oleo SM is a mineralbased delayed-release agent, ideal for use with metallic or wooden formwork for wet precast. It does not stain or affect the colour of the concrete when applied correctly. It is the perfect solution when white cement is used for specialised architectural finishes. In addition, it can handle the high temperatures of steam-curing and prevents rusting in steel formwork.

Chryso® DEM Oleo RT is a hydrocarbon oil-based, delayed-release agent for the roof tile industry, developed specifically for use with aluminium roof tile pallets.

This ready-to-use range of release agents reduces the likelihood of errors, which may occur in other release agents where mixing of various components is required.

When applied correctly and for the specific purpose, the Chryso® DEM range does not modify cement hydration and since it is water-repellent, it is not affected by rain.

These products are manufactured locally by Chryso Southern Africa at its production plant in Jet Park, Johannesburg and comply with regulations for the transport and disposal of hazardous materials.

While generally regarded as a minor item on a bill of quantities, the specification and selection of an appropriate release agent and application method may be critical to the success of the project, affecting both the quality and colour of the surface finish. A release agent is a low-cost item, yet vital in relation to the cost of formwork and moulds. It thus makes sense to use the appropriate release agent for the correct application and formwork substrate, in order to protect and extend the life of the formwork or mould, ultimately resulting in financial benefits.

As each release agent contributes differently to the off-form finish, care in the selection of the release agent is critical.

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