INVESTIGATIONS’ REGARDING VERY ACCESIBILE TECHNOLOGY TO REDUCE CONSTRUCTION COSTS AND IMPROVE THE QUALITY OF THE ASPHALT MIXES BY THE USE OF POLYMERS ADDED DIRECTLY AT THE PLANT MIX

摘要

Polymers are widely used to improve the properties of asphalt mixes. The most popular is PmB modified bitumen by SBS (styrene butadiene styrene thermoplastic elastomer). This solution has some technology difficulties related to the compatibility of SBS with some types of bitumen and the stability of the modified bitumen. For this reasons, thermoplastic plastomers which have polar groups actively interacting with bitumen elements ensuring a better compatibility, are easier to be used. The use of plastomer granules for asphalt mix production allows the reduction of construction costs. This is a very simple technology easy to apply in any conditions even in isolated arias. In this paper we present some laboratory investigations and field applications regarding a procedure to modify asphalt mixes directly at the plant mix by using granular plastomers ( polyolefines) added at the moment of the mix production. We compared the performances of the asphalt mixes produced by plastomer addition at the plant after bitumen, with mixes produced with PMB modified bitumen. We also have studied the performances by using fibers in combination with thermoplastic elastomers and plastomers. We obtained best results for plastomers in combination with fibres. The rheological properties of the asphalt mixes produced by the simplest technology of adding plastomers directly at the plant are meeting all the pavements performance demands. The stiffness is higher and all the other visco-elastic performances are generally very close to that obtained ones using PMB.