Various additives to asphalt binders and asphalt mixtures improving their properties are being used more and more frequently in order to improve the durability of road pavements. Such additives include various types of fibres, including aramid fibres. Tests concerning the impact of aramid fibre addition on the properties of selected asphalt mixtures have been described herein. Two types of asphalt mixtures were assessed: high modulus asphalt concrete (HMAC) and stone mastic asphalt (SMA). The examined asphalt mixtures were assessed with regard to: resistance to rutting, resistance to water and frost as well as fatigue resistance. The conducted tests showed relatively small impact of aramid fibre addition on the improvement of some assessed properties of the analysed asphalt mixtures. The obtained results were also compared to results of the tests conducted by the other research team concerning the impact of aramid fibre addition on the properties of the other types of asphalt mixtures.
The requirements imposed on road pavements are ever increasing nowadays, necessitating the improvement of the properties of paving materials. The most commonly used paving materials include bituminous mixtures that are composed of aggregate grains bound by a bituminous binder. The properties of bitumens can be improved by modification with polymers. Among the copolymers used for modifying bitumens, styrene–butadiene–styrene, a thermoplastic elastomer, is the most commonly used. This article presents the results of tests conducted on bitumens modified with two types of styrene–butadiene–styrene copolymer (linear and radial). Two bitumen types of different penetration grades (35/50 and 160/220) were used in the experiments. The content of styrene–butadiene–styrene added to the bitumen varied between 1% and 6%. The results of the force ductility test showed that cohesion energy can be used for qualitative evaluation of the efficiency of modification of bitumen with styrene–butadiene–styrene copolymer. The determined values of the cohesion energy were subjected to the original analysis taking into account the three characteristic elongation zones of the tested binders. The performed analyses made it possible to find a parameter whose values correlate significantly with the content of styrene–butadiene–styrene copolymer in the modified bitumen. With smaller amounts of added modifier (approximately 2%), slightly better effects were obtained in the case of linear copolymer styrene–butadiene–styrene and for larger amounts of modifier (5–6%) radial copolymer styrene–butadiene–styrene was found to be more effective. This is confirmed by the changes in the binder structure, as indicated by the penetration index (PI).
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