Emulsion Manufacturing: Back to the Basics

The first thing that comes to mind when taking it back to the basics of emulsion manufacturing is the use of quality raw materials. This may seem common-sense, but there are many (often avoidable!) pitfalls of production related to materials and the “recipe” used.

Here we have highlighted 3 areas to keep in mind during the manufacture of high-quality road emulsions:

Water:

A good rule-of-thumb is to start with clean, potable water. This ensures cleanliness and that pH is within an acceptable range. But even with potable water, water hardness can cause issues with certain emulsion types (e.g., tall oil-based products). For example, demulsibility can be impacted due to the presence of calcium and magnesium ions. Here, water softeners may be an effective treatment.

Using other water sources is possible; lakes, ponds and certain types of waste waters have all been used with success. When using a different source, be sure to understand metals content, pH and any kind of treatment the source may go through during the year. Lastly, any water change should be run through a lab mill to ensure stable production and storage, this includes any water used for dilution at the plant or in the field. 

Asphalt:

Across the country, many different asphalt bases are used to produce emulsions: PG 58-28, PG 52-28 (AC-5, 150-200pen), PG 64-22, and hard pen material, in the Midwest alone. Every refinery will be sourcing different crudes to produce these materials. When sourcing your asphalt bases, just like your water, it is important to trial it in the lab. Different asphalt bases can lead to viscosity issues, both low or high, or cause changes in float, demulsibility, etc. A significant portion of problems that are traced back to the asphalt base can be handled through plant operations: additives, latex addition, and chemistry dosage. But proper work upfront will allow you to tweak your formulation if necessary.

Chemistry and pH:

Even with potable water and asphalt suitable for production, care needs to be taken in selecting the proper emulsifier for the job. Certain emulsifiers within the same class (e.g., CQS or “micro surfacing emulsifiers”) can have vastly different properties which can affect both the emulsion properties and mix performance.

Similarly, emulsifier activation through the addition of acid/caustic needs to be diligently monitored to ensure proper solution pH. pH should always be measured using a clean, calibrated, properly stored, and temperature-compensated probe providing reliable measure. It is also advisable to cross-check by comparing the amount of emulsifier to the amount of acid/caustic on a pound-for-pound, or gallon-for-gallon-basis (Measure twice, cut once!). This information, along with specific guidance on emulsifier choice, should be discussed with your chemistry supplier.

Finally, it is important to remember that these three areas speak to materials only, and that successful production of quality road emulsions relies also upon successful manufacturing processes and procedures.

By: Aaron Walker (Ingevity), Stormy Brewster (Marathon Petroleum Corp)