AGGREGATE CHARACTERISTICS AND FRICTIONAL BEHAVIOUR OF DENSE BITUMINOUS WEARING SURFACES

Abstract

The friction between tyre and pavement is an important characteristic for the safe and efficient operation of vehicles. The interaction between vehicle and road surface is a complex phenomenon which is not completely understood. There are a number of variables affecting the skid resistance performance of a pavement. In a skidding situation the main factors which interact are road, tyre, operating condition and driver. A highway engineer has an important role to play in providing and maintaining a safe level of skid resistance. The anti skid characteristics of pavement largely depend upon the aggregates, which comprise more than 90% of a pavement mixture. The aggregates undergo polishing with passage of traffic. It leads to substantial drop in skid resistance of pavement. To maintain a reasonable degree of skid resistance on highway system for anticipated high volume traffic, it becomes increasingly important for the highway engineer to give some thought to aggregate characteristics of mineral aggregates used in pavement construction. The design of pavement wearing course is a primary.factor in achieving a skid resistant pavement surface. The necessity of achieving a skid resistant surface is just one of a number of factors that must be considered by the highway engineer. There are a number of different types of bituminous and cement concrete surfaces. The highway engineer must keep in mind that the choice of a surface type in terms of skid resistance must be balanced with other design parameters. In this study an attempt has been made to analyse the aggregate characteristics and frictional behaviour of dense bituminous wearing surfaces i.e. sheet asphalt and bituminous concrete