Apply a light brush coat of High Bond Primer and allow to dry thoroughly before applying asphalt.
Where vertical or sloping concrete is very smooth (eg. where steel shuttering has been used), the surface laitance should be removed by wire brush or suitable mechanical means to provide a satisfactory key for the asphalt. Where excessive blowing is experienced the fixing of bitumen coated expanded metal lathing over black sheathing felt may be required.
Damage to asphalt and loss of key will be caused by excessive use of mould oil.
Asphalt cannot be applied directly to lightweight concrete of lightweight concrete block work which should be rendered with a suitable sand cement facing or have bitumen coated expanded metal lathing on sheathing felt fixed at maximum 150mm centres.
Joints in brickwork should be flush pointed. The surface must be cleaned and high bond primer applied to avoid blistering or loss of bond.
The key to vertical or sloping timber surfaces if obtained by fixing expanded metal lathing over black sheathing felt fixed by nailing with extra large head galvanized felt nails to BS1202 or with galvanized staples at maximum 150mm centres.