To ensure the proper performance of the project, a mix design should be performed to determine the following:
It should be noted that the design rates are only a guide and should be adjusted for field variances such as pavement conditions and traffic.
Two of most notable scrub seal design methods are the McLeod method and the Modified Kearby method. To find out out more information on each method please click on the links below:
McLeod method: MnDOT Seal Coat Handbook
Modified Kearby method: TxDOT Seal Coat Manual
There is also a webinar that was developed by the Asphalt Institute and ISSA on chip seal mix design procedures which would be the same for scrub seals. The link is below:
A rule of thumb is to add extra binder to the design application rate due to some of the binder being pushed into the cracks. The extra amount is dependent on the severity of the cracking and could be anywhere from 5% more to 20% more.