Your Mixture
Mix design on the job

Sealer manufacturers always supply sealer — whether asphalt or refined coal tar — in a
concentrated form that has to be diluted 25% to 30% by volume with water and mixed with
sand or aggregate for proper textured appearance and non-slip properties. The quantities
of water and sand or aggregate are conventionally expressed as a percentage or quantity
based on the amount of concentrated sealer. For example, 25%-30% water will denote 25-
30 gallons of water added to 100 gallons of concentrated sealer (as supplied by the
manufacturer). Similarly, 2-2.5 lbs. of sand per gallon will mean 200-250 lbs. of sand
added to 100 gallons of concentrated sealer. The sand must be clean, hard, angular and
fall within a specified range of particle size gradation. Too many fine or coarse particles will
detract from performance. The relative quantities of binder (asphalt emulsion or refined
coal tar), clay, and fillers are crucial to the performance of the sealer. Excessive amounts of
clay and fillers in the sealer formulation will produce porous cured films due to insufficient
binder, and thus poor performance. Such sealcoat films tend to lack flexibility and wear
prematurely. Similarly, excessive amounts of sand or aggregate in the mix design degrade
the performance in the same manner. Conversely, an excessive amount of binder (asphalt
or refined coal tar) might produce tackiness under hot climatic conditions, even after the full
cure. Using standard mix designs, both asphalt emulsion sealers and refined coal tar
sealers are capable of suspending sand, holding it in wet film, and keeping it bound  in the
cured film. However, when stretched beyond its capability, the sealer might not suspend
the large quantities (more than 5 lbs.) of sand and definitely will not keep large quantities
of sand bound in the cured film. Sand and aggregates, like any other filler, have their own
binder requirements (the surface of the sand will absorb the binder -refined coal tar or
asphalt- from the sealer). Used in excessive amounts, sand will rob enough binder from
the sealer film which would have been otherwise available to form a continuous film on the
pavement. But for some jobs it is necessary to add larger amounts of sand to fill in the
profile of badly weathered pavements and produce a uniform textured appearance. In such
instances special mix designs using specialty rubber additives are used that offer
satisfactory performance.

Sealcoating can save real dollars for pavement owners. Unsealed pavements will require
repairs starting with the second year and could require a one-inch overlay as often as every
seven years. Cost savings will be a substantial 65% if the pavement is maintained
regularly. Estimated savings for a 10,000-sq.-yd. asphalt pavement are $127,000 over 15
years.