Crumb rubber effect on marshall mix design properties in Lebanon

Abstract

Scrap tires recycling is one major contribution in solid waste management. Crumb rubber resulted from the process of recycling old tires is not only a great environmental solution but it could be a promising modifier to asphalt pavement for its improvement in the engineering properties. Crumb rubber can be incorporated in two methods, the first "the wet process" where crumb rubber is mixed with the hot asphalt before mixing with aggregates and the second "the dry process" where CR is directly added to the aggregates. In this project we studied the effect of crumb rubber on Marshall properties (Stability and Flow) of the Lebanese pavement using the dry process by only adding 3 different CR contents to the optimal binder content resulted by a conventional Marshall mix design but with low binder content (<5%). The aggregates blend is selected according SUPERPAVE standard and LIBNOR (Lebanese standard). Crumb rubber resulted lower stability but higher flow and conventional Marshall Mix design results with low binder content have similar pattern of the curve.