Effect of Type of Modified Bitumen on Selected Properties of Stone Mastic Asphalt Mixtures
Last modified: 2017-02-28
Wearing course is the layer directly in contact with traffic loads and weather conditions. It should be resistant to water and frost, plastic deformations and meet the required threshold of skid resistance. SMA (Stone Mastic Asphalt) is one of the most popular mixture intended for wearing courses of road pavement for very heavy traffic loads. Therefore it contains materials of superior quality. This paper presents the experimental results of selected properties of SMA11 with two typical modified binders (ORBITON PMB 45/80-55, ORBITON PMB 45/80-65) and newly developed highly modified binder (ORBITON PMB 45/80-80 HiMA). These modified bitumens have similar penetration range but they differ in the type of polymer and its contents. Therefore that significantly affects on the differences in standard and functional parameters such as elastic recovery, force ductility etc. The primary purpose of highly-modified binders (HiMA type) is to counteract pavement cracking, plastic deformations and consequently to increase the life span of asphalt courses. It should be noted that tested SMA mixtures had the same aggregate particle-size distribution of mineral mixtures. The study of SMA aimed at determination of the water sensitivity expressed in ITSR (Indirect Tensile Strength Ratio) according to the standard 12697-12 (method A) and rutting resistance according to standard EN 12697-22 in the small apparatus (method B). Comparison of the results of those tests showed some differences between binders and mixtures. Specific situation was observed with rutting resistance where strong SMA skeleton decreased influence of binder type. In addition, evaluation of the skid resistance mixtures of the tested SMA were carried out using the Wehner/Schulze machine. Results may be valuable information for proper maintenance of existing pavements and on the stage of designing.
Highly Modified Asphalt; Stone Mastic Asphalt; Polymer Modified Bitumen; wearing course; Wehner/Schulze machine