INFLUENCE OF WAX CONTENT ON RUTTING PERFORMANCE OF BITUMINOUS CONCRETE.A LABORATORY STUDY

Abstract

India is country with varied types of climatic conditions ranging from 1-11gb Altitude areas in North & North East, desert in West and coastal areas in down South with temperatures varying from _200 C to 600 C . Considerable amount of crude oil(approx 70%) in India is imported from Middle East countries and bitumen is extracted from our own resources i.e all the petroleum refineries right from Assam to Mathura to Panipat to Gujarat etc. Eventually some amount of wax is present in bitumen, whose effects and permissible values have not been yet determined and which needs deliberation. It has been noted that while formulating the new grading system(perfhrmance grade or viscosity grade) for bitumen in India, the effects of natural wax present in the bitumen has - been inadvertently missed out. Penetration Grade specifies the wax content in excess of 4.50/0 is considered harmful as it produces tender mixes due to the lowering of viscosity at 60°C. However, IS:73-2006 and IRC:SP:53-2010 remains silent about the permissible content of natural wax I paraffin wax in the specified grades. The negative effect of the wax in bitumen has been known since ages, natural wax in bitumen may influence binder properties to a larger or minor extent. Considering the increased demand of bitumen in road construction industry (approx 4 Million Metric Tonnes per year in Indian Sub continent) and reduced supply from global suppliers, there is a need to studly the positive effects along with negative effects of wax and to formalize and determine the permissible limits of wax in design mixes without affecting the l)ropeltics and performance of the paveietts. Hence, it is necessary to study the effects of varying wax content in bitumen. Present study is to test and analyse the effect of varying wax content on rutting performance of the Bituminous Concrete (Grade 1, lRC- 1 11:2009) and establish the relationship between wax content and rutting behavior of the Bituminous Concrete layer. Based on the results of various tests the permissible values of wax content in bitumen is also recommended up to 8.2% for rutting behavior as limiting value.