By Mark McLeod
Incorporating additives in pavement sealers is most important. Different sealers require different additives depending on what circumstances the job presents to the contractor. Factors that can affect additive choice include ambient temperature, humidity, pavement temperature, vehicular stress, porosity of the pavement, sand load, and type of sealer. Using the correct additive can mean the difference between a top quality job and a substandard job.
Sealer manufacturers generally polymer modify their sealers in the manufacturing process to "bring all the ingredients together." But that sometimes is not enough to handle other post-added ingredients such as sand and other aggregates. So contractors often need to post-add additives to the mix to encapsulate and suspend the sand in the tank and in the sealer film. (We all know sand is necessary in producing a quality job and a composition with fillers or sand will typically cure faster than a coating without them.)
Whether you are using coal tar, asphalt-based, or a blended sealer, some additives are FAA-specified and designed to encapsulate the aggregates and fillers to create a uniform and continuous film. Water is our best friend but can be our worst enemy in sealcoating. You must have water to dilute sealer to the manufacturer's recommendations, but water can be your enemy when trying to keep sand and fillers suspended in the tank. As many contractors have found out sand and other fillers will fall out of an overdiluted sealer mix. I've often asked contractors, "If you shut off your agitator what happened to the sand or filler by the next morning?" It settled to the bottom of your tank!
The same happens on the pavement, and the sealer film will react the same way. But additives will suspend the sand in the film until all the binder particles have fused and created a tight sealer film through the hydration process. As the sealer dries the additive reacts and assists in this process.
The bottom layer in the sealer film is of most concern as it is the final layer to cure. An additive such as FASS-DRI PSA utilizes nano cure technology, and through molecular-generated heat actually dries the sealer from the bottom up opposed to the traditional top to bottom drying process. Nano technology will also reduce - and in most cases eliminate - severe cutting or tracking of the sealer. The actual process action is called "fugacity," which is the tendency of molecules to escape from liquid and is largely responsible for evaporation.
One of my biggest shortcomings early in my sealing career was not realizing what additives could do for my sealer, and worse, not understanding what additives could do to grow my business. Only after I used additives everyday for a season did I realize just what the features and benefits of additives were.
Additives in your mix allow you to get on the lot for striping in as little as 30 minutes, and in some cases you can open up commercial lots in less than four or eight hours with minimum scarring. You can virtually eliminate any re-emulsification of the sealer once down on the pavement (black water), and additive use disperses sand evenly throughout your sealer film. With proper use of the right additive you can experience almost no sand roll out in the gutters after a rain. Additives will help cure the sealer in high ambient temperature days and when the surface temperature is extreme (reducing significantly tire marks and cutting), and additive use also extends your season, a benefit in both spring and fall.
So given the many advantages using an additive can give you, additives are the most important action you can take to improve both your sealer quality and your bottom line.
Breaking Down the Cost
Additive cost is truly insignificant compared to the benefits of incorporating additives into your daily sealer mix. And once you break down your in-tank cost and realize how much it really added to your square foot cost, you will be sold on adding additives to your sealcoating operation.