EVALUATION OF RUTTING POTENTIAL FOR CRUMB RUBBER MODIFIED BITUMEN IN ASPHALTIC MIXES

Abstract

Flexible pavements with bituminous surfacing are widely used in India. The high traffic intensity in terms of commercial vehicles, over loading of trucks and significant variations in daily and seasonal temperature of the pavement have been responsible for earlier development of distress symptoms. Investigations in India and abroad have revealed that the properties of bitumen and bituminous mixes can be improved to meet the basic requirements. In the present study, an attempt has been made to use crumb rubber modified bitumen (CRMB 55) which is blended at specified temperatures. Marshall's mix design was carried out by changing the modified bitumen content at constant optimum rubber content and subsequent tests have been performed to determine the different mix design characteristics and for conventional bitumen (60/70) also. This has resulted in much improved characteristics when compared with straight run bitumen and that too at reduced optimum modified binder content (5.67%). Specimens for the conduct of wheel tracking test have been prepared using simulated roller compaction equipment and analysis has been caried out to determine the expected number of standard wheel repetitions for both conventional and modified bituminous concrete mixes.