Because emulsions contain water, they tend to behave like water. They will freeze at 32° F (0° C), and will boil at 212° F (100° C). When ambient temperatures are around the freezing point or below 39.2° F (4° C), care must be taken to protect the material. If the temperature of the emulsion is allowed to reach the freezing point, it will usually be damaged enough to render it useless as a workable material. Even after warming to a high temperature, the thawed material will in most cases be broken, the asphalt phase being separated from the water-phase.
One way of handling this problem, is not to use asphalt emulsion during the cold months. However, with proper handling, a certain amount of winter work is possible with emulsions. Keeping the material warm and not allowing it to freeze is the key.
Asphalt emulsions can be damaged by overheating. If the material is heated to the boiling point of water, 212° F (100° C), the emulsion will start to break, just as with freezing.
Emulsions are limited then, to temperatures between 39.2° F (4° C) and 212° F (100° C). In practice, it should seldom, if ever be necessary to heat the emulsion above 185° F (85° C) for any type of a field job. Should heating be necessary, the use of mild heat while gently agitating the material is recommended.
Another important factor in the handling of asphalt emulsion is to recognize the incompatibility of the two different types, anionic and cationic. The two types cannot be mixed. Any storage tanks, transport vessels, or lines handling the one type must be completely cleaned before introducing the other type.
Refer to AEMA's A Basic Asphalt Emulsion Manual for further information regarding the storage and transportation of incompatible emulsion types.
Mild heating of lines, pumps, and valves may be necessary at times when the emulsion has set up or hardened in these small restricted areas. This is especially true at lower temperatures, but sometimes is necessary even in warm weather.
While transporting emulsion in bulk, the transport tank should be as full as possible. This will avoid sloshing the emulsion around within the tank while moving. Transport tanks with baffle plates should be used if available.
Do not pump emulsions excessively. The high viscosity types may tend to lose viscosity if pumped too often or continually.
Pumps used for asphalt emulsion should have extra clearance tolerance between the gears 0.015 to 0.020 in.(0.38 to 0.51 mm), and may be of the positive displacement or centrifugal type. A frozen pump may be broken loose by gently heating from the outside. Refer to ASPHALT EMULSION EQUIPMENT PUMPS for further information.
Some grades of emulsions are designed to be mixed or diluted with water. In those grades that are dilutable, the water should be added to emulsion, never emulsion to water. For the best field performance, the temperature of the water added should be as near the temperature of the emulsion as possible. Also, the water should be potable and free of rust and other contaminants. The emulsion should not be handled in a manner which will cause foaming and incorporate air bubbles. This can cause the emulsion to break. Special care should be taken while loading or unloading. Bottom loading facilities are recommended.
The various grades and types of asphalt emulsion are designed for different jobs, aggregates, methods, etc. Emulsions can vary widely and some require handling techniques that may differ from others. Always check with your asphalt emulsion supplier to find the best way to handle the particular grade or type being used.
In recent years, there has appeared in the market a variety of asphalt emulsions that have been modified with polymer, rubber, elastomers or other modifiers. These materials may or may not require different or special handling techniques. No really general recommendations can be made since there is such a wide variety of materials. Each supplier of the particular product is in the best position to recommend how to handle its own emulsion. Check with your AEMA supplier.