Chemical compatibility of the emulsifying agent with the asphalt cement is essential for producing a stable emulsion. It also determines whether the emulsion is cationic or anionic (or non-ionic). The emulsifier keeps the asphalt particles in suspension and controls the breaking time. The chemical used as an emulsifier greatly influences the properties of an asphalt emulsion. Water that is suitable for drinking may not be suitable for asphalt emulsions. Minerals or other materials in water can affect the production of stable emulsions. Water is the second ingredient in an asphalt emulsion. The properties of the asphalt cement do affect the performance of the residual asphalt on the road. But there is not an exact correlation between the properties and the ability to emulsify the asphalt. Some properties of the asphalt significantly affect the finished emulsion. In most cases, it makes up from 50 to 75 percent of the emulsion. Today’s emulsion manufacturers have many new chemistries available to design the emulsion for the optimal break time and specific use.Īsphalt cement is the basic ingredient of asphalt emulsions. Still others break by a combination of chemical destabilization and evaporation. Some emulsions break by chemically destabilizing the surfactant, others by a simple evaporation of the water. The asphalt particles are surrounded by the ionic charge, which causes the droplets to repel each other and stay suspended in the water.Īll asphalt emulsions are designed to eventually break, or revert to asphalt and water. These soap molecules are like tadpoles, having a hydrocarbon tail soluble in liquid asphalt and an electrically charged or ionic head soluble in water. The emulsifying agent is sometimes called the surfactant, which is composed of large molecules. It is composed of asphalt, water and an emulsifying agent. But, what are they and how are they made?Īn asphalt emulsion is liquid asphalt cement emulsified in water. Asphalt emulsions are an environmentally friendly, energy efficient and cost effective product for use in today’s paving and preservation efforts.
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