Improve Emulsion Stability with Drywell Electric Heating

The team at Process Heating Company, Seattle, reminds contractors that asphalt emulsions—comprising a nonflammable mixture of asphalt, water and emulsifying agents—offer a number of benefits for tack coating and spray patching applications. For example, emulsions have a low viscosity (when compared to liquid asphalt cement) and can be used at low temperatures while still providing good spreading characteristics.

But asphalt emulsions can be tricky to work with.

An emulsion that is too cool won’t flow properly, which can cause issues with a distributor’s pumps. If it’s too hot, it can separate in the tank: the water bakes out of the mixtures, causing coking and damage to the emulsion. Most tack or distributor trucks utilize an open flame via a burner, which heats a tube inside the tank to raise the emulsified mix up to the correct temperature at the beginning of a shift. When the truck is brought back to the shop or yard at night, the mix gets cold, even though the tank is insulated, so it must be reheated at the beginning of the next shift. This repeated heating and cooling of emulsions can cause the mixture to become unstable.

To do their best work, emulsions should be gently brought up to—and then maintained at—the correct temperature. This is a difficult task when heated with burners or direct heat. An alternative method is the electric drywell-style heater, which is ideal because of the even, controlled, gentle heat it provides. With lower-density heat produced through a drywell electric heating system, the heater can be safely run all night or even over a weekend, keeping the emulsion temperature more uniform, and ensuring the distributor is ready for work at the beginning of the shift.

For today’s toolbox tip, consider consistent, gentle heating of emulsions for the morning’s project.