Formwork Lubricants - Types and Uses of Release Agents for Formworks
Excerpt from The Constructor Magazine by Kavita Pai
Concrete formwork lubricants are high-quality form seasonings that are applied to the inner surface of a formwork before pouring concrete. Formwork lubricants are also known as form or mold release agents.
Uses of Formwork Lubricants
Release Agents are used for the following reasons:
Application prevents sticking of formwork to the concrete surface thereby permitting easy stripping of formwork after the concrete has hardened.
Protects the formwork and hence the formwork can be reused several times.
Provides good finishing surface of the concrete with minimum defects.
In the case of wooden formwork, prevents water absorption from concrete by the wooden formwork.
Reduces leakage of water during the curing process.
Prevents steel formwork corrosion.
The performance of release agents are largely dependent on the type of formwork used. For wooden formwork, straight refined, pale, paraffin-based mineral oil and oil-phase emulsion have been successfully used. The oil that is chosen should be capable of penetrating the wood to some extent while leaving the surface slightly greasy to touch.
There should not be any free release agent on the wood surface. The form release agents that are good for wooden formwork are not always suitable for steel formwork. And hence the choose form release agents based on the type of formwork used for construction.
Types of Release Agents:
1. De-Shuttering Oil (DSO)
This is a water-based mold release agent, which produces clean and stain-free, high-quality concrete. It is available in a sprayable form and ready to use as a direct application on required places. It should be applied in light film either by brush or sprayer. If it is over applied, excess release agent should be drained before it dries. Pools of DSO cannot be allowed to dry as it causes surface retardation of concrete.
Advantages of De-Shuttering Oil are as follows:
DSO is economical to use.
It is non-toxic and non-hazardous.
It can be used for all types of concrete formworks.
It helps reduce the cleaning efforts before reusing of the formwork.
DSO provides a damp proof interface that protects the formwork and ensures even texture and color of concrete.
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