Impact of Gradation on the Performance of Fiber-Reinforced Stone Mastic Asphalt

This study evaluates the efficiency of Stone Mastic Asphalt (SMA) as a surface layer on airport runways, with strength assessed by the Marshall Mix Method. Gradations used for prepared specimens were produced according to the parameters specified in the Turkish Highway Technical Specifications, encompassing lower, upper, and mean values, with combinations containing various aggregate types and blended conditions. Bitumen, enhanced with fiber and polymer modification, served as the major binder in all mixes. The tests encompassed stability, flow, air voids, in addition to essential characterizations of aggregate and bitumen. Basalt served as the principal aggregate, while limestone functioned as the filler. The results indicated that certain mixes at-tained the necessary stability for hot mix asphalt layers, with basalt exhibiting superior performance compared to limestone. Coarser gradations resulted in diminished per-formance, whereas limestone combinations demonstrated increased breaking during Marshall compaction, hence modifying the gradation. A dense-graded mixture formu-lated from the average specification limits with a same maximum aggregate size ex-hibited enhanced stability and flow relative to SMA. Analysis of variance (ANOVA) was used to validate the test results.