Use of Shredded Rubber in Unbound Granular Flexible Pavement Layers Author(s): Speir, Richard & Witczak, Matthew Origin: Maryland Date: August, 1994 Categories: Performance Key Words: Rubber, Flexible pavements Summary: The major objective of this research was to conduct a feasibility study into the use of shredded rubber as a partial replacement for aggregate base and sand subbase meeting specifications for the Maryland State Highway Administration were used. The rubber used in this study consisted of a 3rd-4th stage shred product with 60 – 70% retained on a 9.5mm sieve. This size was selected because of its relatively inexpensive cost to produce and because of its adaptability to an aggregate blend. Modified and Standard Proctor tests, CBR tests and M r tests were conducted on the base/subbase-rubber blends with up to 15% rubber content by weight.