Asphaltic Concrete

A dense, continuously graded macadam type bituminous material used for road and airfield construction. Much of the strength and stability is derived from the use of a continuous grading and mechanical interlock of angular coarse aggregate. Binder acts as a compaction lubricant rather than contributing to its strength. Grading specification and binder content tolerances are tighter than for macadams and asphalts, so production control has to be good. A mix design procedure is used to determine optimum binder content with parameters used to ensure maximum stability and mix density are achieved.