International Reports

Report No.	CP19 (jot this number down to order)
Title	Rubber Asphalt Seal Coats
Authors	Scott, Saskatchewan Highways & Transportation
Publisher
Pub. Date	1979
Pages	35 pages
Keywords
Description	During the summer of 1978, eight test sections were constructed to evaluate seal coats using rubber asphalt as binder membrane and graded aggregate as the protective cover. The evaluation was considered necessary to determine whether low cost cold mix and current seal coat surfaces could be replaced successfully and economically by this method of construction. The rubber asphalt was prepared by mixing and heating 25% vulcanized rubber crumb with 75% Saskatchewan AC 6 asphalt cement. The aggregate used was produced by crushing glacial origin gravels. Except for limiting sand and clay sizes, no washing or further processing was done. A description is given of early lavoratory studies and field experiments, the test section sites chosen, construction and equipment problems experiences, initial evaluation and economic analysis. Each test section represented a typical surface type and condition which included primed subgrade, cold mix on subgrade, primed granular base course, asphaltic concrete on granular base and full depth asphaltic concrete. The initial evaluation showed that stone retention is mainly a function of asphalt binder application rate with approximately 2.73 L/m2 (at 15?C) required for 16mm maximum aggregate. Studies also indicated that the graded aggregate specification requiring 35% stone and no more than 6% 71M size was satisfactory. Economic analysis showed that the use of four asphalt distributors and all construction done by Department forces, costs per kilometer for a standard 7.3M traveled way could be reduced to $5,000.
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