Effect of Gradation on Strengthof Bituminous Mixes

Abstract

BCand DBM is a dense-graded bituminous mixture that is used in the base, intermediate, and surface layer of the bituminous pavement structure.These are dense mix and in such mixes, the water cannot penetrate, because can easily penetrate both the semi-dense and open-graded bituminous mix which is commonly used in road construction.  Since 92 to 96 percent by volume of the mixture is aggregate, and hence aggregate gradation and proper contract are important factor in this mixture. The present study examines the effect of gradation of BC and DBM as dense bituminous mixtures on the mechanical properties of mixtures, two granulation fractions were used for each, respectively. In the present study, bitumen VG 40 was used without adding any additives as binder. Conventional Marshall cylindrical specimens were prepared with a different bitumen content from the total weight of the granular material, and volumetric and Marshall Properties were determined. The tensile strength, stability value and flow value of the cylindrical specimens prepared in the optimal bitumen content with various gradations, were investigated. The results show that the second gradations of BC and DBM with NMAS 13.2mm and 26.5mm showed better performance compared to the first gradation with NMAS 19mm and 37.5mm.