Abstract:
Hot Mix Asphalt (HMA) is particulate composite material consisting of mineral aggregates,
asphalt binder and air voids. Asphalt binder is considered as the most expensive and
economically variable material. The increase in energy cost, the need for improvement of
pavement quality and Environmental concerns enforcing the researcher to find alternative
materials to modify the properties of ASPHALT binder.
The aim of this research is to investigating the stability of asphalt mixtures using crumble rubber
and sisal fibers mixes. Common laboratory tests was performed on the modified bitumen asphalt
mix using various proportions of CR-SF and thus analyzed. Marshal Mix design procedure was
used, first to determine the Optimum Bitumen Content (OBC) and then further to test the
modified mixture properties.
From 48 total numbers of samples required for this investigation, 16 samples were used to
determine the OBC and the remaining were used to investigate the effects adding different CR SF percentages to asphalt mix. The OBC was 5.5 % by weight of asphalt mix. Seven proportions
of CR: SF by weight of OBC were tested (0%:1%, 3%:0.9%, 5%:0.7%, 7%:0.5%, 10%:0.3%,
12%:0.1%, and 15%:0%) besides testing of ordinary asphalt mix. Tests include the
determination of stability, bulk density, flow and air voids. Results indicated that CR:SF can be
conveniently used as a modifier for asphalt mixes as a part of sustainable management of
crumble rubber waste as well as for improved performance of asphalt mix.
CR: SF content of 5 %:0.7% by weight of OBC is recommended as the optimum CR: SF content
for the improvement of performance of asphalt mix. Asphalt mix modified with 5.5%:0.7% CR:
SF by OBC weight has approximately above 40% higher stability value compared to the
conventional asphalt mix. Asphalt mix modified with higher percentages of CR: SF exhibit lower
bulk density, higher flow and higher air voids.
