Agrega Gradasyonundaki Değişimlerin Aşınma Tabakasında Kullanılan Bitümlü Sıcak Karışımların Mekanik Özelliklerine Olan Etkilerinin İncelenmesi

Abstract

Gradation properties of the bituminous mixture in Turkey, according to the layer to be used, are specified in the Highway Technical Specification. In this study, it was aimed to investigate the effects of five different aggregate gradations created as lower, middle and upper limits as well as by offsetting the lower and upper limits of the Type-1 gradation envelope defined for wearing course in the specification on the mechanical properties of bituminous mixtures. With the determined five gradations, both the effect of variations in the gradation envelope and the expansion potential of the gradation envelope were investigated. For this purpose, Marshall designs were applied on the bituminous mixtures created with different aggregate gradations. According to the test results, optimum bitumen requirement of the mixture increased as the aggregate gradation got thinner. It has been determined that as the gradation gets thinner, the void filled with bitumen ratio (Vf) and the percentage of voids in mineral aggregate (VMA) increase, while the unit weight (Dp) decreases at the optimum bitumen ratio. At the same time, it was observed that the gradation envelope defined for Type-1 may have an expansion potential.