Bitumen Emulsions for Road Construction

The main objective of laying asphalt concrete mixtures as a road surface is to ensure its adhesion to the bottom layer.  A practical solution to this problem is -using bitumen emulsions.

Bitumen emulsion disperse system consists of: bitumen and water.  Thus the smallest particles of bitumen are dispersed in water without being mixed with it.

According to the type of emulsifier, all emulsions are divided into two types: cationic and anionic.  Road builders primarily use cationic bitumen emulsions, as their disintegration occurs chemically.  The disintegration of anionic bitumen emulsions is achieved by evaporation of water.

Bitumen emulsions are divided into EBC (Effective Binder Content) types:

  • quick-setting emulsion (EBC-1);
  • medium-setting (EBC-2);
  • slow-setting(EBC-3).

Each of these types has its own field of application: EBC-1 and EBC-2 – the roads construction, and EBC-3 – pothole repair.

Another important technical indicator for EBC-1 and EBC-2 is – viscosity. When viscosity is low, emulsion is not thick enough and will flow down from higher areas and accumulate in lower areas.  This phenomenon results in uneven adhesion between layers and further pavement deformations during exploitation.

In case of too high viscosity, the strips will appear instead of integral and uniform coating, which also contributes to bad adhesion between the layers.

Viscosity of bitumen is determined by penetrometer – a compact instrument with a needle.  The viscosity limit is measured according to the depth of needle penetration.  Penetrometer is not suitable for bitumen emulsion because their density is close to the density of water.  Therefore, to evaluate the relative viscosity of bitumen emulsion, a viscometer is used.

Relative viscosity depends on granulometric structure : grain concentration and grain size of the material.  It can be  adjusted  using a colloid mill, designed for dispersing bitumen in water medium.  By changing the size of the gap  between a rotor and a stator of the colloid mill – achieves the change in granulometric structure.

Also relative viscosity may be affected by emulsifier (it’s type and amount).

GlobeCore bitumen emulsion plants are:

  • UVB-1 with capacity of 1 m3/h;
  • UVB-1 with capacity of 2 m3/h;
  • UVB-1 with capacity of 8 m3/h.
обновлено: May 16, 2016 автором: globecore