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. 2020 Oct 30;13(21):4864.
doi: 10.3390/ma13214864.

The Use of De-Vulcanized Recycled Rubber in the Modification of Road Bitumen

Barbara Gawdzik  1 , Tadeusz Matynia  1 , Krzysztof Błażejowski  2
Affiliations

The Use of De-Vulcanized Recycled Rubber in the Modification of Road Bitumen

Barbara Gawdzik et al. Materials (Basel). .

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.

Keywords: SBS; bitumen; chemical modification; de-vulcanization; recycled rubber.

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Conflict of interest statement

The authors declare no conflict of interest

Figures

Figure 1
Figure 1
Scheme showing the chemical modification of the studied bitumen.
Figure 2
Figure 2
Results of differential scanning calorimetry (DSC) analysis of fresh rubber (1); rubber heated at 190 °C for 2 h to which sulfur was added (2); rubber heated at 190 °C for 2 h to which sulfur and SBS were added (3).
Figure 3
Figure 3
Relations between the penetration top/penetration bottom for the bitumens modified at: (a) 190 °C and (b) 220 °C.
Figure 4
Figure 4
Relations between R&B top/R&B bottom for the bitumens modified at: (a) 190 °C and (b) 220 °C.
See this image and copyright information in PMC

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