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What are the surface course and binder course thickness?
Thickness of surface courses and binder courses are detailed in Appendix A3 to A7. All surface courses on flexible roads are 40 mm thick as shown in the Appendices. All binder courses within flexible roads finish 100 mm below the surface and are 60 mm thick.
However, the bituminous structural courses may extend below this and become part of the base (road base). The line on the diagrams A3 to A7 differentiating between the binder course and base (road base) was shown to clarify where foam concrete could be used as part of the base (road base) as per table A9.1 in Appendix 9.