Road Science emulsion additives are designed to elevate key aspects of end-use performance. To effectively manage upgrading aging infrastructure, the industry needs longer lasting and cost effective maintenance treatments. Road Science emulsion additives extend life and improve the durability of maintenance treatments by providing better emulsion adhesion to aggregates and protecting the treatment through time from moisture damage.
Cationic Emulsion Additives
There are three major classifications of emulsion grades: rapid-setting, medium-setting, and slow-setting. The terms “rapid,” “medium,” and “slow” relate to the amount of time it takes for the emulsion to cure and the amount of mixing that can be performed before the emulsion breaks. Emulsions that allow for the longest mixing times generally take the longest to cure, while emulsions that allow for very little mixing time are those that set and cure most rapidly.
Chemical surface-active agents, serving as emulsifiers, are classified by the electrochemical charge that is attained when they dissociate in a water solution. In the case of cationic emulsions, the chemical charge is positive. The chemical type and quantity of surface-active agents used in the manufacturing process governs the process in which the resulting asphalt emulsion can be used.
Anionic Emulsion Additives
The term anionic bitumen emulsion is derived from the migration of particles of bitumen under an electric field. The droplets migrate toward the anode (positive electrode), and hence the emulsion is called anionic. In an anionic emulsion, there are “billions and billions” of bitumen droplets with the emulsifying agent at the water bitumen interface.
The tail portion of the emulsifying agent aligns itself in the bitumen while the positive portion of the head floats around in the water leaving the rest of the head negatively charged and at the surface of the droplet. This imparts a negative charge to all the droplets. Since negatives repel each other, all the droplets repel each other and remain as distinct bitumen drops in suspension