STRESS-STRAIN RELATIONSHIP FOR ASPHALT CONCRETE IN COMPRESSION

Experiments on short term static compression of asphalt concrete speci mens, differing in aggregate, compaction effort, bitumen percentage, s ize and type of loading, demonstrate a common pattern in the stress-st rain relationship, identical to that long known for cement concrete an d rock. Beyond the limit of linearity 'swelling' of asphalt concrete s pecimens is visible to the naked eye, analogously to cement concrete. When the friction between specimens and press platens is reduced, asph alt concrete undergoes a splitting type of failure, again like cement concrete. In the light of this similarity, the problem of asphalt conc rete behaviour under short term compression is considered from the poi nt of view adopted for cement concrete and rock. In the atrophy model the nonlinear behaviour of cement concrete in the ascending branch is ascribed to its degeneration due to the microcracking process. Applied to asphalt concrete, the model agrees well with experimental results.