Study of the effect of four warm mix asphalt additives on bitumen modified with 15% crumb rubber

Abstract

Due to a growing concern over global warming, the bituminous mixture industry is making a constant effort to diminish its emissions by reducing manufacturing and installation temperatures without compromising the mechanical properties of the bituminous mixtures. The use of mixtures with tyre rubber has demonstrated that these mixtures can be economical and ecological and that they improve the behaviour of the pavements. However, bituminous mixtures with a high rubber content present one major drawback: they require higher mixing and installation temperatures due to the elevated viscosity caused by the high rubber content and thus they produce larger amounts of greenhouse gas emissions than conventional bituminous mixtures.This article presents a study of the effect of four viscosity-reducing additives (Sasobit® 1 , Asphaltan A® 1 , Asphaltan B® and Licomont BS 100 s ) on a bitumen modified with 15% rubber. The results of this study indicate that these additives successfully reduce viscosity, increase the softening temperature and reduce penetration. However, they do not have a clear effect on the test for elastic recovery and ductility at 25 °C.

An investigation on using pre-treated tyre rubber as a replacement of synthetic polymers for bitumen modification

“…Also, the polymer cross-link density would be reduced as severe temperature could cause breaking of the cross-linking network of polymer corresponded to a gradual reduction in the modification level (Abdelrahman 2006). Limited studies have considered applying warm-mix technology additives (WMA) to the RTR-MBs in order to lower the mixing and compaction temperatures and allow better workability and handling , Akisetty et al 2011, Rodríguez-Alloza et al 2013). On the other hand, fewer studies have considered using devulcanised rubber by the cleavage of cross-linking sulphur bonds in rubber vulcanizates without cleavage of the polymer chain bonds, this resulted in improving the dispersion and interfacial adhesion of RTR and binder (Dong et al, 2011;Liang, 1999;Liang & Woodhams, 1998;Xiao-qing et al, 2009).…”

“…Also, the RTR-MBs cannot be stored for long periods after production because of the lack of compatibility between RTR and binder that leads to a phase separation problem. Many studies have been conducted to produce RTR-MBs that have reduced HTV and/or extended shelf life characteristics (Zanzotto and Kennepohl 1996, Glover et al 2000, Attia and Abdelrahman 2009, Akisetty et al 2011, Rodríguez-Alloza et al 2013. Some researchers utilized much severer curing conditions and fine rubber particles to overcome or alleviate these problems (Zanzotto and Kennepohl 1996, Glover et al 2000, Attia and Abdelrahman 2009).…”

A Review of Warm Mix Asphalt Technology: Technical, Eco-nomical and Enviromental Aspects

“…Another recently developed organic wax is Licomont BS 100, which is added in amounts of 3 % and 4 % by weight of asphalt. At these percentages, a significant reduction of the asphalt binder is obtained, increasing its resistance to permanent deformations and hardness (Rodríguez et al 2013). Other organic waxes, along with their descriptions, can be found in Rubio et al (2012).…”

Hybrid input–output life cycle assessment of warm mix asphalt mixtures

“…Asphalt mixtures containing this additive have reported good engineering properties (Hurley and Prowell, 2005). For this study, the wax was added to the mixtures in the amount of 2% and 4% by total weight of the bitumen, as previous studies have shown that these dosages are able to achieve a lower viscosity (Rodríguez-Alloza et al, 2013. Although some studies have quantified the potential environmental impacts of WMA in terms of emissions and resource consumption, the role of the upstream supply chains of the different materials used to produce the asphalt mixtures have generally not been included.…”