Evaluation of reliability of RILEM fragmentation test

Black Curve and White curve are a well-known method to fully characterize a RAP source, however involves a major effort in terms of laboratory equipment and time-consuming process. RILEM has validated two protocols for a fast RAP characterization: Fragmentation test and Cohesion test. In this study, the authors show the results of a reliability evaluation of the Fragmentation test. Considering this test evaluates the stability of aggregates gradation of the RAP under compaction, the authors have induced an artificial variation in the RAP gradation source to create different RAPs that can be considered just apparently the same. A certain amount of RAP aggregates has been gradually replaced with steel slags to assess the sensitivity of this test. One source of RAP has been used and three different batches were selected: 100% RAP, 50% RAP + 50% steel slags and finally 100% steel slags. Steel slag aggregates have been chosen because of its low Los Angeles abrasion coefficient and its increasingly use on hot mix asphalt with RAP. A series of laboratory tests have been performed using the modified Proctor, as required by the investigated RILEM protocol, and the percentage of material passing through a control sieve has been assessed. The obtained results are encouraging, as they fit with the initial assumption that RAP sources with different percentages of RAP clusters are differentiated by the Fragmentation test. Thus, a simple job site laboratory can provide a key information on the quality of the material to be used on field applications.