Bohdan Dołżycki

Behaviour of Asphalt Concrete in Cyclic and Static Compression Creep Test with and without Lateral Confinement

ABSTRACT The paper presents results of the cyclic and static compression creep test conducted on asphalt concrete specimens with and without lateral confinement. Asphalt concrete containing three polymer modified bitumen and one pure bitumen was tested. The results have shown that behaviour of asphalt concrete tested with and without lateral confinement significantly differs. It has been found that in creep without confinement the cohesion of a mix is mainly responsible for its response to external load whereas in creep with lateral confinement both cohesion and internal friction of mineral aggregate play an important role. It has been proven that the creep test without lateral confinement overestimates the function of bitumen and underestimates the function of internal friction of aggregate. Lateral confinement is of the greatest importance in cyclic loading in which lack of confinement may very significantly increase creep of material. The creep rate at cyclic loading was found to be significantly higher that the creep rate at static loading of the same magnitude of acting stresses for the same material. The prediction of asphalt mix behaviour in a pavement structure and evaluation of asphalt mix quality based on the results of unconfined compression creep tests may not be fully reliable.