Published: October 2014 | Category: Activity management , Research programme , Research & reports | Audience: Roading contractors
The research investigated aspects of the use of epoxy modified bitumen for construction of chip seals. Changes in the shear modulus, needle penetration and cohesive energy of the epoxy bitumen were used to monitor changes in the material as it cured at 35℃ and 45℃ and after accelerated ageing at 85℃ for 177 days. Wheel-tracking tests were used to determine the ability of the material to resist chip embedment and flushing. The adhesion to aggregate and resistance to water-induced stripping was also measured.
Epoxy bitumen curing rates would enable seal construction within timeframes used with conventional binders. However, although the ultimate strength of the materials was satisfactory, the curing rate would be too slow for epoxy bitumens to be useful as a lower cost substitute for commercially available high-friction surfacing binders.
Epoxy bitumen demonstrated good resistance to water stripping without added adhesion agents. Epoxy bitumen seals were highly effective in resisting chip embedment into a soft substrate and potentially might be a means of controlling or eliminating flushing in the field.
The materials used in this study were prototype formulations that may need to be optimised for low temperature flexibility. Further investigation is needed to properly characterise low temperature behaviour.
Keywords: adhesion, chip seals, durability, epoxy modified bitumen, flushing
