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PennDOT Approves Liquid Fuels for Fog Seals

Monday March 4th, 2019
Townships may use liquid fuels funds to apply a combination of a seal coat with a fog seal on local roads now that PennDOT has approved design procedures and specifications for this treatment. 
Although municipalities have been using fog seals and bituminous seal coats — also known as chip seals — to improve the surface and extend the life of their roads for years, PennDOT only recently granted approval for fog seals or the use of both treatments together. Design procedures and specifications for seal coats were approved previously. 
A fog seal is a thin application of an asphalt emulsion to an existing pavement surface with or without a fine aggregate cover, while a bituminous seal coat is a thin application of an asphalt emulsion covered with a single layer of course aggregate. 
PennDOT developed and approved this specification with input from the Pennsylvania Association of Asphalt Material Applicators. During the specification development, workers monitored the test sites for performance, and after seven years, the experimental areas still performed better than the control areas. 
Specifications for the use of fog seals on seal coats can be found in Publication 408/2016, Change No. 5, under Section 472, Bituminous Fog Seal for Bituminous Seal Coats. The publication is available online.