Performance assessment of hot mix asphalt with chemically stabilized rubber bitumen

Abstract

The use of crumb rubber from vehicle tyres in hot mix asphalt production has been a very promising option in the field of waste recycling and sustainability. The disposal of used vehicle tyres has been a serious and difficult issue. Due to their indestructible nature the options are burning or disposal, none of these are desirable in our global environment. The trials for using crumb rubber in hot mix asphalt started in the 1920s; these early applications used the so called dry method, where the rubber is considered as part of the aggregate instead of the binder. This method did not deliver the expected higher performance, and researchers have been looking into the so called wet process since the 1960s, where the rubber is added to the binder, modifying its properties. The modified binder is then added to the aggregate during asphalt production. Although many countries utilise the crumb rubber using the wet process, there is an ongoing problem with this technology, similarly to the application of polymer modified bitumens (PmBs): the storage stability of the product. This short-term segregation problem has been preventing the wide application of crumb rubber bitumen in road construction. Additionally, the high viscosity of product may cause difficulties during manufacturing and paving which should be considered when selecting aggregate grading. MOL Plc. developed and patented a procedure for producing chemically stabilized rubber bitumen (CSRB); the pilot scale production started in 2012 and the facilities are capable to produce 5000 tonnes of CSRB-equivalent of 150,000 tyres-in their Zala Refinery, Hungary. This paper discusses an asphalt research program conducted at Budapest University of Technology on a 10mm nominal aggregate size wearing coarse hot mix asphalt. This study presents the comparative analysis of asphalts containing PmB and CSRB separately. Prepared samples were subjected to performance based and related mechanical testing. The findings summarised in this paper suggest that performance of asphalt mixes produced with CSRB binder are similar or equivalent to asphalt mixes produced with PmB with regard to moisture sensitivity, stiffness and wheel tracking, while the low temperature cracking test showed higher and superior performance.

Dynamic Viscosity Prediction of Blends of Paving Grade Bitumen with Reclaimed Bitumen

“…• The viscosity values predicted by Kendall-formula were very far from the measured values. • The research of following related topics is planned in the near future: correlation between T BTSV and σ BTSV values, for polymer and rubber modified bitumens; determination of the influence of SBS and rubber in the blends containing bitumen from recycled asphalt; performance assessment of hot mix asphalt with chemically stabilized rubber bitumen (Petho and Toth, 2012;Toth et al, 2016).…”

Assessment of Impact of Aramid Fibre Addition on the Mechanical Properties of Selected Asphalt Mixtures

“…Not only polymers are used to modify asphalt binders and mixtures. Researchers also dealt with other additives, as indicated in the literature, including crumb rubber [ 5 , 6 , 7 , 8 , 9 ] produced as a result of waste tyre processing as well as natural asphalts [ 10 , 11 , 12 ].…”