Specification 49 Stone Mastic Asphalt for Airfields - Ministry of Defence

Specification 49 Stone Mastic Asphalt for Airfields Appendix B – Straightedge Test
Appendix B – Straightedge Test
B.1 SCOPE
This Appendix shall be followed to determine the
surface accuracy of bituminous surfacing layers in
this Specification.
B.2 APPARATUS
B.2.1 The straightedge for the tests shall be
purpose made and 3 m long. It shall have a flat
square edge of metal, at least 75 mm wide, along
the full length of its base. The straightedge shall
be fitted with lifting hand grips or handles.
B.2.2 A calibrated wedge may be used to
determine the straightedge clearance. The wedge
should have an angle of (5.75 ± 0.05)°, and
engraved at 10 mm intervals across the incline,
starting at the apex, representing clearances
increasing in 1 mm intervals up the incline.
B.3 PROCEDURE
B.3.1 The straightedge shall be placed
unsupported on the surface, anywhere in any
direction, other than across the crown of a camber
or across a drainage channel. The location shall
be selected by the Project/Works Services
Manager or his representative, and the tests shall
be carried out in his presence.
B.3.2 Twenty tests shall be made for every
1000 m² laid and at least half of these tests shall
be across lane joints.
B.3.3 The Contractor shall mark with white paint
all areas which fail to comply with the specified
requirement.
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