Executive Summary : | Government initiatives to minimize production cost and environmental impact led to the development of warm mix (WM) modified asphalt binders throughout the world. There are many implication realized for the adoption of warm mix asphalt (WMA) technology in terms of evaluation of workability of asphalt mixes and quantification of the effect of reduced production temperature on performance. The traditional belief of considering reduction in viscosity offered by WM additives cannot be completely used as a justification for reduction in mixing and compaction temperature of asphalt mixes produced using this technology. Hence it is important to understand the complexities related with WMA technology and define the mechanisms related to its constructability. Also the benefits and risk associated with the performance of WM modified binders in terms of resistance to distress and moisture damage has to be studied for optimizing the amount of additive dosage to be used for satisfactory results. In this study, two viscosity graded (VG) asphalt binders: VG 10 and VG 30 will be used. Each of the base binder will be modified using three different WM additives: Asphamin, Sasobit and Rediset. In order to assess the effect of aggregate minerology on the optimum dosage of WM additive to be selected, two different aggregate type (limestone and granite) will be used for preparation of asphalt mixes with two different aggregate gradation (Bituminous Concrete (BC) and Stone Mastic Asphalt (SMA)). The study will begin with binder characterization tests on the conventional and well as WM modified asphalt binders. Tests such as penetration, softening point, viscosity, performance grading (PG) using dynamic shear rheometer (DSR) and Fourier transform infrared spectroscopy (FTIR) will be carried out. Next, the effects of WM additive and aggregate gradation on workability of asphalt mixes will be studied. Ball on three plate arrangement using DSR will be taken for studying the tribological behaviour of binders. The quantification will be done using the Stribeck curve obtained from the test. Following the test on binders, a torque tester will be used to study the effect of aggregate gradation and aggregate type on the workability of characteristics of asphalt mixes. Further, the performance properties of the binders will be assessed using multiple stress creep and recovery (MSCR) test and linear amplitude sweep test (LAS) test at varying range of test temperatures (10-60 ?). Finally, the moisture sensitivity of WM modified binders will be studied using bitumen bond strength (BBS) tester. The different form of analysis done in various phases will be used in an optimization strategy for selecting the best combination and dosage of WM additive for achieving the desirable performance of the asphalt binders. The whole process can be considered as modelling the allowable temperature reduction based on the performance and workability of the WM modified asphalt binders. |