2. Interactions with formwork and release agents

2.1 Influences of release oils

The role of form release agents, often composed of mineral- or vegetable-based oils, is to maintain a film of water at the interface between formwork and fresh concrete, and to perpetuate the lubricating effect of this layer in order to limit excessive shear forces (the layer of water at the interface between formwork and fresh concrete can be destroyed by aggregates approaching the surface, or can be weakened by the texture of the formwork). In most cases, friction at the interface between formwork and fresh concrete is not sufficient to completely destroy the micrometer-thick film of oil present on