Influence Of Coarse Aggregate Shape Factors On Bituminous Mixtures

Abstract

Aggregates are the principal material in pavement construction. Conventional road aggregates in India are natural aggregates obtained by crushing rocks. The physical properties of coarse aggregate are more significant in new generation bituminous mixtures. Aggregate characteristics such as particle size, shape, and texture influence the performance and serviceability of hot mix asphalt pavement. The shape of aggregate particle has significant influence on performance of the Bitumen pavement. Particle shape can be described as cubical, blade, disk and rod .The strength serviceability requirements of Bitumen mixes such as stability, flow, voids in mineral aggregate (VMA), voids filled with bitumen (VFB) and air voids are highly depend on the physical properties of aggregate. Dense bituminous macadam (DBM) mixes were analyzed with different proportions (10%, 20%, 30%, 40%, 50%) of different shape of aggregates were studied. Mixes with cubical and rod shape aggregates has been showed good results on stability. The parameters such as air voids and voids in mineral aggregate increases with increase in proportion of blade type of aggregates in DBM mixes. The particle index value of coarse aggregate significantly affected the engineering properties of Hot mix asphalt (HMA) mix. The particle shape determined how aggregate packed into a dense configuration and also determined the internal resistance of a mix. Mixes prepared by replacing 20% aggregates shown higher stability values. Cubical particles exhibit interlock and internal friction, and hence results in greater mechanical stability than the blade, rod, and disk shape aggregates. Particle shape parameter values obtained were higher for cubical shape aggregates and lower for blade shape aggregates.