Bleeding or flushing

The only cause for bleeding is the excess amount of bitumen present in the asphalt layers or tack coat. Hot summer months accelerate bleeding as well as traffic if asphalt layers are overcompacted. Excessive sealant in crack filling may also cause bleeding. 

In severe and extensive bleeding, the only effective treatment is through the removal and replacement of surfacing. 

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Bleeding or flushing of bitumen is the upward movement of bitumen and its appearance in the surface of the pavement. This results in the formation of a film of bitumen on the surface of variable thickness. Figure 15.18 shows a typical bleeding. 

Bleeding or flushing of the binder results in a surface that is too rich in binder. Bleeding can cause hazardous conditions owing to loss of surface skid resistance. 

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