Crumb rubber modified bitumen: A waste-based sunscreen for roads
New Study of Rubberised Asphalt
Rubberised asphalt has been around for a long time and its proponents have an armoury of arguments for its use. However, a new study into the impact of UV light on rubber modified bitumen suggests that rubberised asphalt can protect road surfaces from UV degradation.
This study investigates the effect of UV radiations on the chemo-mechanical properties of neat and modified bitumen with different concentrations of crumb rubber and compares it to that of thermal ageing.
Samples were aged in the Q-Lab weatherometer for 869 h at 0.89 Wm-2, equivalent to one year of UV radiations energy in the city of Melbourne, Australia, in 2019.
Fourier transformation infrared (FTIR) spectroscopy was used for analysing the changes in chemical bonds before and after ageing. It was found that thermal ageing results in the development of carbonyl and sulfoxide oxides while evaporating the volatile components, as depicted by the decreasing value of the aliphaticity index.
On the other hand, UV ageing mainly targets components with bond energy lower than 413 kJ/mol, i.e., C–C, C–O and C–H that usually consist of aliphatic chains of hydrocarbons. The rheological test results revealed that both thermal and UV ageing produce stiffer materials, as depicted from the upward shift of the master curves. However, this shift reduces with the increase in CR concentration. All unaged samples were found to lay well below the Glover-Rowe onset damage envelopeonset damage’ threshold, while crumb rubber modified bitumen was almost 60 kPa away from the damage zone. Moreover, if neat bitumen is to be modified with 22.5% of CR, it can reduce the damage produced by UV and thermal ageing by approximately 50%, hence showing greater resistance to thermal and solar radiation degradation.
The complete study is available at ScienceDirect, an Elsevier Publication.
