A STUDY ON RHEOLOGY OF MULTIPLE BITUMEN MODIFIERS

Abstract

India has large highways and road networks. The traffic on Indian highways is of mixed type and different in character as compared to many other countries.Conventional bituminous materials have been used satisfactorily in most of the highways and runway applications. But during the last decade due to increase in axle loads, severe climatic conditions, heavy traffic and construction failures led to a need to enhance the properties of the original bitumen. Environmental factors such as temperature, air, and water can have a profound effect on durability of asphalts. The ideal bitumen should be strong enough, at high temperatures, to withstand rutting or permanent deformation, and soft enough to avoid excessive thermal stresses, at low pavement temperatures, and fatigue, at moderate temperatures. So it is important that properties of the bituminous binder should be improved by addition of the polymers or some other additives to improve the road performance. At present, modified bitumen has become popular due to its ability to reduce rutting at high temperatures and also reduce the occurrence of thermal cracking which generally takes place at low temperatures. This Study mainly focuses on the improvement of the properties of modified bitumen by using various combinations of modifiers. In this study, rheological tests have been conducted on VG 10 grade bitumen and modified bitumen having various combinations of neat bitumen, polyethylene, SBS, EVA, and sulphur. It does not include the tests on bitumen mixes. It was found that sulphur increases the stability of' modified bitumen storage and thus enhances the properties. The values of G*/sin6 for EVA and sulphur combinations are higher than SBS and sulphur modified bitumen binders at lower frequencies but at higher frequencies, SBS and sulphur combination provide better results. It indicates that EVA with sulphur provides higher rutting resistance under loading compared to SI3S at higher temperatures. l)ynamic amplitude sweep tests were also conducted to characterize the bitumen binder in the study. Results indicate that complex modulus increase with the increase in the frequency, percentage of modifier and modifier combination. EVA and S combinations lower phase angles. Modified binder shower lower strain as compared neat bituminous binder at same stresses.