As the degradation of aggregates affects the properties of bituminous concrete, various aspects connected with degradation are studied in this article. These include the effect of the method of representation of degradation, the necessity of using an appropriate method to represent degradation, and the effect of type and pattern of grading on degradation. It is observed that the amount of degradation and the order of the gradings change depending on the method adopted to represent it. The defect in using the more popular method (i.E., The surface area method) to represent the degradation of dense gradings is explored, and the authors show that representing degradation by percent increase in the fine aggregate of a grading is more appropriate. The selected dense gradings (i.E., Fullers, practical continuous, skip and semigap gradings) used in different countries in three maximum sizes (25 mm, 20 mm, and 12.5 Mm) are degraded in the los angeles abrasion machine by a modified procedure to study the effect of maximum size, type, and pattern of the gradings on degradation.It is observed that semigap-type gradings degrade less, and the pattern of gradings is important in the degradation of aggregate gradings. This paper appears in transportation research record no. 1228, Asphalt mixtures and asphalt chemistry.
Abstract