Abstract
Rubber from recycled car tires and styrene-butadiene-styrene (SBS) were used for the chemical modification of commercially available road bitumen 50/70 (EN 12591). The modification process began with the addition of rubber into asphalt and heating the whole amount at the temperature of 190 °C or 220 °C. Under such conditions, de-vulcanization of rubber took place. Next, SBS and sulfur as a cross-linker were added and the heating was continued so that cross-linking of SBS and the de-vulcanized rubber proceeded. In the studies on the influence of rubber concentration on the final properties of asphalt 10% or 15% of rubber was considered. Chemical modification reactions were performed within 2, 4, and 8 h. The results showed that both the modification at 190 °C and 220 °C affected the properties of the base asphalt efficiently, although the asphalt modified at 190 °C contained more non-degraded rubber. Increasing the modification time led to dissolution of the rubber crumbs and its de-vulcanization. Bitumens modified in this way are characterized by high storage stabilities. Their behavior at low temperatures also deserves attention.
Highlights
The increased traffic loads and improvement of pavement working have led to the development of polymer modified bitumens (PMB) during the last few years [1]
The aim of our research was to determine whether the resulting products would have properties comparable to those of polymer modified bitumen (PMB), if recycled rubber was used as a modifier
Technologies for producing road bitumens with the use of rubber are known, but in the mentioned technologies, rubber is usually used as a cross-linked polymer [25,26]
Summary
The increased traffic loads and improvement of pavement working have led to the development of polymer modified bitumens (PMB) during the last few years [1]. The added polymer intensifies the binder properties and allows for the construction of better quality roads. The addition of polymers causes a significant increase in production costs and complications related to their storage. The low compatibility between the asphalt and polymer can lead to phase separation when the product is stored at a high temperature without mixing [1]. The polymer-rich phase concentrates on the top. This upper part exhibits high viscosity and is useless for paving applications
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