Relation Between Air Voids And Bitumen Content In Bituminous Concrete (BC) Mixes

Abstract

Flexible pavement is popular in many countries. Flexible pavement in the form of Hot mix asphalt is a mixture of aggregates, bitumen as a binder and air voids. Many authors have estimated the factors affecting durability of the mix. Durability of HMA is affected by the presence of void system and sensitive to bitumen content. This paper is aiming to find association between content of bitumen and air voids in the bituminous concrete (BC) mixes. The bitumen of Viscosity Grade-30 and aggregates of siliceous sandstone and basalt are used in this study. The samples have been collected from two different sources one from Sheikhpura and other from Mirza chowki for establishment of relationship. It was found that on increase in actual bitumen content the percentage air voids decreases and its vice-versa. It is found that the actual air voids differ than the designed air voids because of difference in the amount of compaction in the field and in the laboratory. So, this difference in percentage air voids is significant and the designed air voids which is essential in Marshall mix design method for better performance in real practice. which indicates towards a requirement of reduction in the minimum bitumen content for BC as described in the MoRTH. As bitumen consumption reduces, the cost will drastically reduce.