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 Rutting Characteristics of Conventional and Modified Bituminous Concrete Mix
-Rutting is defined as the accumulation of small amounts of unrecoverable strain resulting from applied loads to the pavement. In sort it is a vertical depression observed in road in longitudinal fashion. Due to repeated heavy axle wheel load, on the path of wheel this depression occurs longitudinally. The present investigation is carried out to propose the use of waste plastic and crumb rubber in bituminous mix of flexible pavements in order to improve their performance and also to give a way for safe disposal of plastic wastes and crumb rubber to provide a solution to threat of environmental pollution as well. In this study the dry process is used for waste plastic modified bituminous concrete mix and wet process is used for crumb rubber modified BC mix. The Marshall method of mix design is adopted to find the optimum bitumen content. Rutting in conventional BC mix at optimum binder content and in both modified (crumb rubber and waste plastic) BC mix by adding 10% crumb rubber and 10% waste plastic is determined at 40 0 C, 50 0 C and 60 0 C by passing 2500 number of passes at 0.7 MPatyre pressure. Minimum rutting is observed in waste plastic modified mix. Effect of variation of binder content on rutting is also studied in conventional and modified mix and it is found that on increasing or decreasing binder content beyond OBC the rut depth always increases.
DEVELOPMENT AND USE OF THE REPEATED SHEAR TEST (CONSTANT HEIGHT): AN OPTIONAL SUPERPAVE MIX DESIGN TEST
Investigators studied rut development in asphalt pavements in order to establish the foundations for the prediction of rutting in pavement structures. This paper presents some advances in the characterization of asphalt-aggregate mixes by using finite element technology to predict permanent deformation. Although fatigue and thermal cracking may affect permanent deformation, such mechanisms are not discussed as they are considered of secondary importance.