The effect of crumb rubber in dense graded and open graded cold mixture asphalt

Recycling tires is one of the eco-friendly way for reducing environmental problems.
Incorporating crumb rubber in asphalt mixtures is an alternative way for reusing the end-of-life
tires in road construction. The main purpose of this study is to evaluate the cold mix asphalt
incorporating crumb rubber as a substitute for a part of fine aggregates. In this study, the
aggregate gradations for mix design were selected according to the specification, Dense
Graded Emulsion Mixtures (DGEM) Type IV and Open Graded Emulsion Mixtures (OGEM)
Type E/20. The design bitumen content in this study was optimized for stability, void in
mixture (porosity), and density. Crumb Rubber (CR) emulsion mixtures were made with
optimum bitumen content at 8% by mass of total mixture for DGEM and OGEM. In order to
incorporate crumb rubber into the cold emulsion mixtures, laboratory testing were performed
for 25% and 50% of fine aggregates replaced with an equal volume of crumb rubber. In
general, CR emulsion mixtures showed good results in all parameters. The CR emulsion
mixtures also had a good comparison to hot mix asphalt specification for medium volume
traffic loads with porosity less than 10%. From this study, crumb rubber can be recommended
as a substitution material of fine aggregates in cold mix asphalt.