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.
Low cost device for evaluating rutting characteristics of bituminous mixes
One of the most common pavement distresses occurring on major highways in India affecting performance of pavements is rutting or permanent deformation. The subgrade, subbase and/or bituminous layers contribute to rutting. Even though bituminous mixes in India are usually designed to meet the Marshall Mix Design criteria specified by the Ministry of Road Transport & Highways (MoSRTH this will help to achieve performance-based specifications for bituminous mix for durable pavements. Performance-based specifications and tests have already been incorporated by various agencies for their mix design. One means of evaluating rutting performance of bituminous mixes is wheel tracking devices. They have become more popular, as they simulate great extension of the moving wheel loads and environmental conditions. However, the majority of these devices currently available in India are imported, difficult to maintain and expensive. Keeping that in mind, the IITKGP Rut Tester has been developed by the Transportation Engineering Division of Indian Institute of Technology (IIT), Kharagpur. This is a simple wheel tracking device, developed indigenously, which may be used to evaluate mixes. Tests were conducted on bituminous mixes, in order to demonstrate some of the capabilities of the device. Details and salient features of the device, as well as results of the testing, are presented in this paper.
Deformation Mechanism in Asphaltic Concrete
A theoretical approach is presented to describe the permanent deformation mechanism in asphaltic concrete subjected to traffic simulated dynamic loading. The approach is based on mechanical energy concepts and leads to a better realization of the rutting mechanism in flexible highway pavements. A power relationship between the rate of permanent strain accumulation and the number of dynamic load repetitions was derived. Two parameters were introduced in this relationship: exponential parameter “m” and intersection parameter “A.” The first parameter, m, is dependent on the material type. Parameter A is a function of stress‐strain pattern and intensity, stress level, and dissipated plastic strain energy during the dynamic loading. The derived relationship was experimentally verified with excellent correlation. Parameter m was showed to be constant for all samples of the same material tested under various conditions. Regression analyses showed that “A” was a function of the applied deviator stress and the res...