Dopravní stavby - Fakulta stavební - Vysoké učení technické v Brně

12th International Scientific Conference, April 20-22, 2009 Brno, Czech Republic 1293. Used functional Tests of asphalt mixturesAt the beginning of the project, functional tests for AC-wearing and binder course were chosen.For the AC 11 surf-mixtures the determination of water sensitivity according to ČSN EN 12697-12 [2]and stiffness according to ČSN EN 12697-26 [5] were applied, for AC 16 bin-mixtures thedetermination of water sensitivity, fatigue according to ČSN EN 12697-24 [3] and stiffness.Regarding the Cyclic Compression Test according to ČSN EN 12697-25, it was planned at thebeginning of the project to build the testing equipment and start the tests without deriving the limitingvalues. The reason for this was that there had been no experience with this test in the Czech Republicand the standard ČSN EN 13108-25 was still uncompleted at the beginning of the project. All the testswere carried out for the mixtures I, III and IV.4. Setup of the limiting values in the national annex ČSN EN 13108-1 – functional approachAll the measurements described above were aimed at the final setup of the limiting values in thenational annex of ČSN EN 13108-1 Asphalt concrete. Experience with the designing of asphalt mixtureshas demonstrated that the sieve curves designated as “I” and “IV” for both AC 11 surf and AC 16 bin donot represent routinely designed asphalt mixtures because of the following two deficiencies: the mixture“I” is too fine and has low VMA. To fulfil the demand on the void content it is necessary to lower thebinder content and in this way also the bitumen film thickness. These mixtures are very resistant againstrutting; on the other hand, however, because of the lowered binder thickness they have low durabilityand can disintegrate. This can be seen on low values of water sensitivity test. The mixtures “IV” arecoarse graded with high VMA and therefore also high binder content. These mixtures have lowresistance against rutting but achieve high values of water sensitivity. Also because of the thick bitumenfilm, there were achieved very good results regarding fatigue [7]. From this point of view the idealmixtures are based somewhere between these two extremes. From this knowledge the limiting valuesmentioned in the following tables were derived. The mixtures designated as AC 11 surf S and AC 16surf S are for very high traffic, whereas the mixtures designated as AC 11 surf + and AC 16 surf + arefor high-traffic pavements.Wearing coursesType S +Designation of the mixtureAC 11 surf S,AC 16 surf SAC 11 surf +,AC 16 surf +Water sensitivity – min. ITSR (%) 80 70Functional requirementsMinimal stiffness S min (MPa) 7 000Resistance against permanentdeformation – Triaxial f c max(μm/m/n)will be addedTable 2: Chosen requirements for wearing courses in the national annex, ČSN EN 13108-1