Determination of fine aggregate angularity in relation with the resistance to rutting of hot-mix asphalt

Rutting in asphalt pavements continues to create problems for pavement agencies. One factor that has been identified in determining asphalt pavement rutting susceptibility is the fine aggregate angularity (FAA) in the asphalt aggregate mix. The aim of this study is to investigate the angularity of fine aggregate produced in Turkey and to draw the attention of design engineers to this subject. To examine the relative effect of angularity of fine aggregate on the passing time through an orifice, material was obtained from 30 different sources which represent a wide range of materials used in Turkey. This collection offered a variety of geometric irregularities. The aggregates included 4 natural sands and 26 crushed aggregates. ASTM C128 “Specific Gravity Test of Fine Aggregate” and AFNOR P18-564 “Determination of Flow Rate of Fine Aggregate” which has been adopted by AFNOR were performed on each sample. Rutting tests were then performed on four different aggregate samples which had different FAA values and which were crushed by different crusher types. Test results bring to light that factors like the mineralogical properties of the fine aggregate and the crusher type must be considered in determining the angularity of fine aggregate. Also rutting test results showed that higher FAA values increased resistance to rutting of hot-mix asphalt.