Creep modulus of asphalt mixes determined in uniaxial cyclic compression test with "some confinement"

The paper presents the results of laboratory testing and analysis of several variables that affect the value of the Creep Modulus determined in the Uniaxial Cyclic Compression Test “with some confinement”, according to EN 12697-25 standards. The study, at the Experimental Road Laboratory of the University of Padova, was performed by means of the Nottingham Asphalt Tester on both dense graded as well porous asphalt mixes. The influence of the following variables was analysed: stress level, loading time, rest period, curing period (which is the ageing of the ready specimen, undisturbed, at room temperature before testing), testing temperatures and sample size. The purpose was also to compare the “some confinement” procedure with the traditional unconfined uniaxial cyclic compression test, which is not included in the standard. The results of this study indicate that the “some confinement” procedure could have a different influence on the Creep Modulus depending on the volumetric properties of the mix being studied and the testing conditions.