Investigation the effect of together usage of three different additives on the properties of bitumen and bituminous hot mixtures

Various additives are commonly used to improve the properties of bitumen and bituminous hot mixtures. These additives are mainly crumb rubber, polymer and warm mix additives. While there are studies in the literature on these additives in single and double combinations, there is no study on triple usage. In this study, the effect of single and triple use of crumb rubber (CR), polymer (SBS) and warm mix (Sasobit(R)) additives on the properties of bitumen and bituminous hot mixtures were investigated. Rotational viscosimeter, softening point, penetration, dynamic shear rheometer and bending beam rheometer tests were applied to bituminous binders while Marshall stability and flow, indirect tensile strength, indirect tensile stiffness modulus, indirect tensile fatigue and dynamic creep tests were applied to bituminous hot mixtures. In single use, SBS and CR increased viscosity and Sasobit decreased viscosity. Viscosity values increased in triple usage due to high CR and SBS content. The softening point values of modified binders compared to pure binders increased while the penetration values decreased. The rutting parameter values of the modified bitumen increased. While the low temperature performance of SBS and Sasobit modified binders worsened in single uses, CR showed no significant effect on the low temperature performance of binders. Marshall stability and indirect tensile strength values increased with the use of additives in bituminous hot mixtures. Similarly, fatigue life, indirect tensile stiffness modulus and creep stiffness of mixtures produced with modified binders increased. When the cost and the performance criteria of binders and mixtures are evaluated together, it is found that the use of CR, SBS and Sasobit additives together is more advantageous than the use of SBS which is the most commonly used additive in flexible pavament.