1, the impact of temperature
Asphalt and water temperature is more important process parameters, the temperature is too high or too low will affect the emulsification effect of asphalt. Low temperature, poor mobility, too high, not only the consumption of energy, increase costs, but also make water vaporization, resulting in changes in the concentration of the emulsion, that is, the proportion of asphalt with water changes, while generating a large number of bubbles, reduce product quality , The stability of emulsified asphalt decreased. In addition, for the nonionic emulsifier, as the temperature increases, the hydrogen chain is gradually destroyed, its hydrophilic decline, especially close to the emulsifier "cloud point", the emulsion stability decreased significantly. In general, the average temperature (i.e., the emulsion temperature) after mixing the asphalt and water is preferably controlled at 80 ° C to 70 ° C or less.
2, storage temperature
Emulsified asphalt with the storage temperature increases, its stability is getting worse, and even the group (block), which is due to the continuous evaporation of water emulsion, the higher the temperature, the faster evaporation. Especially in the surface of water loss serious, significantly change the ratio of oil to water, making the surface of the demulsification crust, which stratified agglomeration, the internal emulsion at higher temperatures, asphalt particles to accelerate the movement of particles, particles and particles between the collision opportunities increased Part of the emulsion demulsification, resulting in oil and water separation, thus affecting product quality. Therefore, the product produced, as soon as possible to the emulsion temperature down, to avoid affecting the stability of the product storage. Recommendation: When purchasing emulsified equipment should be equipped with anti-corrosion performance of the heat exchanger emulsified asphalt production equipment, both energy and also ensure the stability of emulsified asphalt.
3, the role of machinery
In the emulsion storage, operation of the pumping, transfer, and in the course of the application of mixing, treatment and so will make the emulsion by various forms of mechanical shear. This will give the bituminous particles a considerable amount of energy. When this energy exceeds the activation energy of the coalescence, the asphalt particles will cross the potential barrier and the emulsion will lose stability and agglomerate. It will give the emulsion production, a variety of processing and application difficulties, especially in the need for direct use of the emulsion of the occasion, the results of the condensate to make it lost its value.
4, frozen and dissolved
When the emulsion encountered low temperature conditions will occur when the freeze, freeze and ablation will affect the stability of the emulsion. Frozen emulsion after melting, ranging from emulsion surface viscosity caused by increased, while the emulsion is caused by the cohesion. So in the transport or storage process should pay attention to antifreeze. The reason why the freezing will affect the stability of the emulsion is due to water after the ice to expand, the accumulation of ice crystals in the asphalt particles between the enormous pressure to force them close to each other, and finally coalescence together. The most commonly used antifreeze is to add antifreeze to the emulsion. The most commonly used antifreeze is methanol, ethylene glycol and glycerol, these substances can reduce the freezing temperature of the emulsion.
5, the impact of long-term placement
The emulsion is agglomerated during the long-term placement due to the collision between the asphalt particles during the Brownian movement. At the same time, due to the role of gravity will lead to asphalt particles settling or floating, and the formation of cohesive layer. No matter how high the stability of the emulsion, in the long-term placement process will inevitably form irreversible agglomerates and was demulsified. Therefore, the shelf life should be specified for the emulsion. Practice has proved that the stability of emulsion placement and asphalt particles size, system viscosity and environmental conditions and other factors.
Therefore, emulsified asphalt is a thermodynamically unstable system, the stability is only relatively speaking, asphalt emulsion damage will eventually occur, by analyzing the factors that affect the stability of the emulsion, intended to emulsion production, storage, operation, the use of the process, Try to avoid these unfavorable factors, to maintain the relative stability of the emulsion.