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Characterization of Permanent deformation. Mondher Neifar, Hervé Di Benedetto, Berthe Dongmo. NABin Conferense - 26. october 2004. Berthe-Julienne DONGMO-ENGELAND. …. 1980. 1960. 1950. 1990. 1970. The problem is solved. Apparition of rutting. Rutting reappears.
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Characterization of Permanent deformation Mondher Neifar, Hervé Di Benedetto, Berthe Dongmo NABin Conferense - 26. october 2004 . Berthe-Julienne DONGMO-ENGELAND
… 1980 1960 1950 1990 1970 The problem is solved Apparition of rutting Rutting reappears Rutting in France: milestones • Evolution in the production of bitumen • Evolution of axle loads configuration
15 to 50 cm Arase de terrassement Couches de surface Plate –forme support de chaussée Accotement Roulement Liaison Base Couches d’assise Fondation Couche de forme 1m Partie supérieure des terrassements Sol support Origins of rutting in bituminous roads Bituminous layers Unbound layers
Aim • Homogeneous test • rheological model • Measure both “large” (10-2) permanent deformation and “small” (10-6) cyclic deformation • complex modulus
Test developed Triaxial test on bituminous mixes h=12cm d=8cm
Test developed Triaxial test on bituminous mixes • High resolution • A mechanical system to move axial targets • Temperature regulation
s s max t Type of loading Cycles & rest periods
1 Possible to obtain Complex modulus Experimental Great strain evolution Cycle N & N+1 0<t<2p/fr
s s max t Cyclic loading periods Rest periods Experimental Stress Time (s) Compression and tension type tests T = 25°C; smax = 0,4 Mpa; f = 1Hz
Strain-number of cycles 0.3% Cumulated number of cycles Experimental T = 25°C; smax = 0,4 Mpa; f = 1Hz T = 25°C - f = 1 Hz smax = 0,4 MPa
s s max t Phase I Phase III Phase II Small strain measured Experimental General curve for continuous loading T = 35°C; smax = 0,4 Mpa; f = 1Hz Information in the linear domain (LVE)
Tests • 0/14 Bituminous mixes • 35/50 bitumen at 6.8 ppc
Stress Time (s) VEL or classical VP laws not adapted Experimental Influence of frequency T = 25°C smax = 0,4 MPa
Experimental Tests in compression
Phase 3 enorm = 58.59N0.1951 Frequency Temperature Stress level Experimental Cyclic compression tests Type : e = f(N) e0 deperm= f(sjmax)
Traction Compression Volume variation Compression Tension
Complex modulus evolution f = 1Hz smax = 0,4 MPa
Conclusion • New test • Permanent deformation • Small cycle properties • Results for compression and extension tests • Classical laws not adapted • Cyclic effect • Suitable developments • Prediction