The influence of particle shape and surface texture (roughness) on physical properties of soils, portland cement concretes, and asphalt cement concretes hasbeen of interest to highway engineers for many years. These particle characteristics have shown effects on the compactibility, strength, and durability of these paving mixtures. However, the topic of this paper is concerned principally with those effects on properties related to compacted mixtures of asphaltic concrete. The classification of particle shape and surface texture for use in determining specific effects on the properties of asphaltic concrete has been based on visual examination, measurement of flow rate, or measurement of volume of voids. Amethod is presented for determining a shape-texture index (sti) by measuring a flow rate of the -no. 8 Sieve size portion of fine aggregate. It is suggested that this simple, fast procedure could be used for field (construction) control ofthe -no. 8 Material in a hot-bin. Data are presented to show sti value effects on (a) the compactibility of aggregate densified by three methods, (b) voids in the mineral aggregate of asphaltic concrete, (c) marshall and hveem stability values of asphaltic concretes, and (d) creep modulus of asphaltic concrete. This paper appears in transportation research record no. 1259, Chip seals, friction courses, and asphalt pavement rutting 1990.
Abstract