Studies on Effect of Wheel Configuration-Temperature and Type of Binder on Rutting Characteristics of Bituminous Concrete Mix
This report presents the investigation of rutting characteristics of bitumen mixes using plain bitumen (VG-10) and modified binders (CRMB-60 and PMB-70). The report will be of particular interest to engineers in the public and private sectors with responsibility for the design, construction, maintenance and rehabilitation of HMA pavements. The present work is aimed at understanding the properties of mix and the machine parameters which influence the deformation causing ruts for mixes. The rutting was caused on the beam specimens prepared in the laboratory. The study includes the influence of different types of binders, air voids, and along with the applied loads on the rutting characteristics. The results are analyzed to formulate regression equations. It is found that modified binders resist rutting compared to plain binders. PMB-70 binders perform better than VG-10 and CRMB-60 binders under the laboratory induced applied pressures and number of passes.
A Study of Nonlinear Tire Contact Pressure Effects on HMA Rutting
ABSTRACT The Indiana Department of Transportation/Purdue University accelerated pavement testing (APT) facility has been utilized in a number of studies of hot mix asphalt (HMA) rutting performance. The benefit of using APT is that rutting performance can be established in a few days of testing. Finite element (FE) models have been developed for relating APT to in-service pavement performance. Factors addressed in the models include pavement geometry, boundary conditions, materials, loads, test conditions, and construction variables. Determining the effects of these factors provides a means for better interpreting APT test results and HMA rutting performance. A detailed analysis using 3D and 2D FE has been made of tire/pavement contact pressure effects on rutting. The analyses include tread pattern and constant and varying contact pressure. A creep model is used to represent the HMA time-dependent material behavior. Based on test data, the material constants in the creep model were back calculated. Result...
RUTTING RATE ANALYSES OF THE AASHO ROAD TEST FLEXIBLE PAVEMENTS
Asphalt concrete (AC) fatigue cracking, AC low-temperature cracking, and pavement surface rutting are the flexible pavement distress modes normally considered in flexible pavement analysis and design. AC fatigue cracking and rutting in component pavement layers (AC surface, granular base and subbase layers, and subgrade) are related to structural responses (stress-strain-deflection). Pavement rutting is discussed. One practical and applied pavement rutting approach is to correlate structural responses (stress-strain-deflection) with field distress measurements. The forms of laboratory-based material/soil distress models are helpful in establishing the general parameters that best define the structural response-field distress measurement relationships. The NCHRP 1-26 Phase 1 Final Report indicated that the log permanent strain (epsilon sub p)-log load repetitions (N) phenomenological model was an appropriate, versatile, and practical approach. Paving materials (AC and granular base/subbase) and subgrade soils generally follow the model. It is assumed that a phenomenological pavement surface rutting model would be of the same form. An analogue, a proposed pavement surface rutting rate (RR) model is evaluated: RR = RD/N = A/(N supra B), where RR is the rut depth in inches, N is the number of repeated load applications, and A and B are terms developed from field calibration testing data. The RR model was validated by analyzing selected AASHO Road Test data and rutting performance information from Illinois Department of Transportation rehabilitated sections of the AASHO Road Test flexible pavement tangent sections. The analyses indicated that the RR concept is valid. Stable pavement rutting trends were related to ILLI-PAVE estimated pavement structural responses, particularly the subgrade stress ratio. Similar RR performance (the B values in the RR equation) was noted for the original AASHO sections, reconstructed sections built with salvaged AASHO materials, and new sections constructed with similar paving materials. The RR approach can be effectively used in a priori pavement analysis and design and pavement management system activities. For the typical "generic specification" flexible paving materials used by a highway agency, the B terms and relationships relating structural responses to A can be established from a flexible pavement performance data base.