Effective Prime Coats for Compacted Pavement Bases

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T.J. Freeman, J.W. Button, C.K. Estakhri

Publication Date:

August 2010


Prime coats have long been used to seal the surface pores in the base, reducing the migration of moisture and absorption of the first application of surface treatment binder. Prime coats also strengthen the granular base near its surface, binding the finer particles of aggregate, and help protect the base from inclement weather and limited vehicular traffic before the next pavement layer is constructed. Prime coats promote adhesion between a granular base and a subsequently applied bituminous surface of the base by penetrating the voids near the surface. The main objective of this research project was to evaluate the effectiveness of prime coats and determine which combinations of methods and materials provide the most benefit to TxDOT. Testing methods and equipment were developed to measure the penetration of the prime coat into the base course and to determine the increase in adhesion and cohesion at the surface of the base course provided by the prime coat.

Report Number:



Prime Coat, Pavement Primer, Highway Construction, Base Construction, Hot Mix Asphalt

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