BituPlus is a reputable supplier of high-quality anionic bitumen emulsion. The production of bitumen emulsion involves the dispersion of bitumen in water with the aid of a surfactant. Therefore, the choice of emulsifier is a critical factor that significantly influences the quality and characteristics of the product. Emulsifiers are surfactants, and they are categorized based on the charge of their particles. Given the extensive use of water bitumen emulsions as binding and film-forming materials in construction, two primary types of emulsifiers are employed: anionic and cationic.
Surface-active agents, which function as emulsifiers, are classified based on the electrochemical charge they acquire when they dissociate in a water solution. In the case of anionic emulsions, the chemical charge is negative. The type and quantity of the surface-active agent utilized in the manufacturing process dictate the specific applications for which the resulting asphalt emulsion is suitable.
The term anionic bitumen emulsion is derived from the movement of bitumen particles under an electric field. These droplets migrate toward the anode, which is the positive electrode, hence the designation “anionic.” In an anionic emulsion, countless bitumen droplets are dispersed with the emulsifying agent at the water-bitumen interface. The tail portion of the emulsifying agent aligns itself within the bitumen, while the positive portion of the head remains in the water, giving rise to a negatively charged surface on each droplet. This negative charge causes all the droplets to repel each other, resulting in the suspension of distinct bitumen drops. Below is a representation of a typical anionic emulsifying agent, along with a diagram illustrating the orientation of the agent at the bitumen-water interface and the negative charge conferred upon each droplet.
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ANIONIC EMULSION |
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| RS | MS | SS |
| RS-1 | MS-1
HFMS-1 |
SS-1 |
The difference lies in the electric charge: anionic bitumen emulsions carry a negative charge, while cationic emulsions are positively charged. The choice of emulsifier used in the emulsion preparation plays a crucial role in determining the efficiency and reliability of the product.
For specific reasons, cationic systems offer significant advantages over anionic emulsions. In road construction, many fillers contain a limited quantity of positively charged particles that can attract the negatively charged particles found in anionic emulsions. Consequently, creating a uniform structure and achieving a high degree of adhesion with an anionic surfactant can be more challenging. In the case of anionic emulsions, bitumen often needs to be modified with additives, whereas cationic emulsions rely on the emulsifier itself to serve as an adhesion additive.
Unlike cationic emulsions, which readily interact with both alkaline and acidic minerals, anionic emulsions exhibit less versatility and are most effective when used with alkaline minerals.
The quantity of emulsifier applied directly affects the emulsion’s breakdown rate, which refers to the duration until the bitumen, separated from the emulsion, returns to its original state.
