Altering sealer mix design

• Within the mix design range recommended by the manufacturer, use only as much water as is needed for proper flow and workability. Excessive water reduces the cured film thickness and may result in premature wear.
• The amount of sand/aggregate may be adjusted according to the pavement usage. A smaller amount of sand might be acceptable for low-traffic pavement with a tight profile while a higher sand loading may be essential for rough pavement, medium traffic, or inclined surfaces.
• The sand/aggregate loading should not exceed 4 to 5 lbs. per gallon of the concentrated sealer because, being filler, sand will absorb binder as well as water. By absorbing binder, the sand becomes an integral part of the coating. Above 5 lbs. sand absorbs too much binder to be available for adhesion to the pavement. The coating becomes too rigid to flex with the pavement, and the pavement might show adhesion problems.
• Mesh size of the sand/aggregate must be within 50 to 60 mesh size range because the finer the sand, the higher the number of particles per pound, and the higher the total surface area and higher binder absorption will be. Sand with 100 mesh size has eight times the number of particles and twice the surface area than 50 mesh sand. The binder and water absorption is directly related to the surface area.
• Use additives where they add a definite value or solve a situation. Ask your supplier about the specific role of the recommended additive and how it will benefit the overall performance.
• Ignore suggestions to use vinegar, Elmer's glue, or magnesium chloride, etc. as additives. They may damage your sealer. When in doubt, discuss your plans with your materials supplier.

Girish Dubey is president of STAR Inc., Columbus, OH.