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

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.

Special Issue: Characterization of Innovative Asphalt Materials for Use in Pavement Design and Analysis

“…Twenty universities and scientific centres contributed with their original research papers to this Special Issue of Materials . The issues covered can be divided into five main topics: Characterization of recycled materials in asphalt concrete mixtures, such as waste of sanitary ceramics [ 23 ], crumb rubber (CR) from waste tires [ 24 , 25 , 26 ] and reclaimed asphalt (RA) [ 27 , 28 ]; Investigation of natural [ 28 ] or bio-based [ 29 ] materials used as rejuvenators in recycled asphalt applications; Study of rheological and fatigue behaviour of bituminous materials with [ 30 ] and without [ 31 ] the use of renewable bio-materials; Evaluation of lubricant characteristics of graphite nanoplatelets [ 32 ]; Fatigue life prediction model for materials employed on long-span steel bridge decks [ 33 ]. …”

“…Characterization of recycled materials in asphalt concrete mixtures, such as waste of sanitary ceramics [ 23 ], crumb rubber (CR) from waste tires [ 24 , 25 , 26 ] and reclaimed asphalt (RA) [ 27 , 28 ];…”

“…The study presented by Gawdzik et al [ 25 ] was aimed at investigating the process of modification of bitumen with crumb rubber, paying particular attention to the rubber addition percentages (10 and 15%), mixing times (2, 4 and 8 h) and mixing temperatures (190 and 220 °C). The results showed that both temperatures improved the properties of the base bitumen, although the bitumen modified at 190 °C contained more non-degraded rubber.…”

Evaluation and Comparison of Mechanical Properties of Polymer-Modified Asphalt Mixtures

“…Asphalt binders can be made harder by modification. Different types of modifiers were tried worldwide to enhance the rheological properties of asphalt binder, such as polymers [1][2][3][4][5][6], crumb rubber [5,[7][8][9][10][11], waste plastic [12][13][14][15][16], geopolymers [17], and nano-materials [18][19][20][21]. Polymers are commonly used to modify and improve the rheological properties of asphalt binders.…”

Influence of Type of Modified Binder on Stiffness and Rutting Resistance of Low-Noise Asphalt Mixtures

“…The increased content of air voids requires the use of high-quality modified bitumen, which significantly determines the durability of the pavement in operating conditions. Positive results are obtained with the use of binders modified with the addition of SBS copolymer (e.g., Kraton 1192), CR from used car tires and a combination of these two modifiers [ 4 , 5 , 6 ]. Modifiers of this type contribute to a greater range of viscoelasticity, increasing the softening temperature, improving the resistance to technological and service aging, and increasing low temperature cracking resistance [ 7 , 8 ].…”