Rheological Properties and Moisture Susceptibility of WMA Mixture Containing Moist Agregate

The objective of this study was to investigate and evaluate the rheological and moisture susceptibility of the WMA mixtures containing moist aggregates. The experimental design included the utilizations of two aggregate sources, two moisture, two anti-stripping additives, and three WMA additives and control. Several properties of the binders and mixtures were obtained including： viscosity, dynamic shear rheometer, beam bending rheometer of WMA binders, indirect tensile strength （ITS）, tensile strength ratio （TSR）, and flow values. The experimental results indicate that the WMA additives can result in a slight decrease in viscosity and an increase in failure temperature. In addition, the moisture susceptibility results illustrated that the mixtures containing moist aggregates generally have similar ITS values to other mixtures regardless of HMA or WMA types. Moreover, there were no significant differences in the wet ITS values of WMA mixture amongst four types of mixtures under identical conditions （same moisture and lime contents） except for the mixtures containing liquid anti-stripping additive and Asphamin additive.

Mixture Performance of Bitumen Modified with Cocamide Diethanolamide

Bituminous binders have been modified by using cocamide diethanolamide.The chemical material used in this study is used for the first-time on the purpose of modification of the bitumen.In addition to the conventional bitumen tests(penetration,softening point and ductility tests),adhesion and peeling tests(Vialit,Nicholson and California tests)were carried out on the bituminous binders which are modified with different ratios of cocamide diethanolamide.According to the results of the tests,the most appropriate additive ratio has been determined.Samples containing the reference bituminous binder and the bituminous binder modified with the most appropriate cocamide diethanolamide ratio were prepared using the superpave volumetric mix design method(SuperpaveTM).In accordance with standard method of test for resistance of compacted asphalt mixtures to moisture-induced damage(AASHTO T 283),the moisture susceptibility of prepared samples has been examined.In order to observe the changes in strength due to the temperature difference,prepared samples were subjected to the freeze-thawing test in accordance with standard test method for resistance of concrete to rapid freezing and thawing(ASTM C 666).

Utilization of Ripe Coconut Fiber in Stone Matrix Asphalt Mixes

Stone Matrix Asphalt(SMA)is a gap graded mix;characterized by higher proportion of coarse aggregate,lower proportion of middle size aggregate and higher proportion of mineral filler.In the present laboratory study,commonly available one conventional VG 30 bitumen and another modified binder,namely CRMB 60 have been used along with a non-conventional natural fiber,namely coconut fiber which is abundantly available in India to provide improved engineering properties and at the same time preventing the usual draining of binder in SMA.The role of a particular binder and fiber with respect to their concentrations in the mix is studied for various engineering properties.Marshall procedure has been followed to determine the optimum binder and optimum fiber contents and also to study the relative advantages of fiber addition in the SMA mixtures.Thereafter,the engineering properties under both static as well as repeated load conditions and moisture susceptibility characteristics have been studied.It is observed that only a marginal 0.3%coconut fiber addition brings significant improvement in the engineering properties of SMA mixes.

Durability Properties of Materials and Mixture Composition of Bitumen Stabilized Materials

Bitumen Stabilized Materials (BSMs) are widely recognized as environmentally friendly through significantly reduced energy consumption,reduced emissions and reuse of high percentage of RAP and recycled pavement materials. In order for these materials to be cost effective,their life-cycle performance needs to be proven. Durability of BSMs is a long-term phenomena that requires consideration during mix design. Time is very important variable for performance consideration under field conditions. The factors that influence durability and long-term performance of BSMs include the mineral aggregates,binder and mixture compositions. In this study,the important,but less understood aspects of durability properties of BSMs were investigated. These include wear and tear of mineral aggregates,age-hardening of binder (foamed bitumen and bitumen emulsion) and moisture susceptibility of typical mix composition. The wear and tear was investigated using Durability Mill Index (DMI) test,binder ageing was investigated for short and long-term effect,and moisture susceptibility was investigated by pulsing water pressures using new device i.e. moisture induction simulation test (MIST). The accelerated moisture conditioning simulates field conditions whereafter retained shear properties are evaluated. The results found that durability of mineral aggregates is significantly influences by the type and nature of mineral composition. The ageing of binder occurred in both short and long-term conditions,with short-term effects being dominating the foamed bitumen properties during laboratory production. Moisture susceptibility is significantly influenced by the mix compositions of aggregates blends with and without RAP,with different bitumen binder types (foamed bitumen or bitumen emulsion) and active filler type (cement or lime) and contents. The evaluation and ranking of mixes which are resistant and susceptible to moisture damage was done using retained cohesion (RC) after dry and wet monotonic triaxial testing.