Evaluation of the effect of processed plastic additives on the properties of road bitumen

Modified bituminous binders are widely used in road construction. Various types of modification are known; SBS polymer modification is considered the most advantageous and popular. The article presents the results of research focused on the possibility of modification of typical road binders in a different manner, i.e. by using processed recycled plastics. The basic requirement in the case of this type of modification is that storage stability of the obtained material is ensured and that performance properties of the material do not deteriorate in comparison to those of the base binder. The work presents chosen test results of materials obtained by blending conventional road bitumen 50/70 and 70/100 with additives produced from PP, PS, LDPE, HDPE (and their combinations). The additives were obtained in the process of pyrolysis, using different production parameters - processing temperature and time. Basic tests were performed on 56 different bitumen-additive blends in order to identify the most promising variants for further wider analysis. A method for objective selection of the best bitumen-additive blends was proposed. The proposed method is not a classic ranking method (attribution of points); it is based on an objective function composed of three component functions, which correspond to individual blend parameters and are assigned adequate weights. The method may be adjusted by selection of weights or use of different component functions. Based on the adopted method, additives with the most advantageous properties in terms of use in asphalt mixture production were identified.