Bitumen emulsion

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Bitumen emulsions are colloidal mixtures of road construction bitumen and water. Due to the different surface tensions of the two liquids, stable emulsions cannot be produced by simply mixing them. That is why emulsifiers and stabilizers are used. Their chemistry ( pH value ) is used for a twofold division into anionic (basic) and cationic (acidic) emulsions . A further distinction is made between unstable (U), semi-stable (H) and stable (S) emulsions. When the emulsified bitumen comes into contact with the rock, a firmly adhering bitumen film forms (referred to as “breaking”). The 0.1–50 μm bitumen particles practically suddenly form a continuous bitumen film by coagulating and separating from the water, which then evaporates.

With quartz-rich rocks there are often adhesion problems with anionic emulsions, so that in this case cationic emulsions achieve better adhesion. The extensive spectrum of bitumen emulsions is not adequately covered by standardization. DIN EN 13808 for cationic bitumen emulsions has existed since July 2005 .

application areas

The bitumen emulsion is used in road construction and building protection .

Anionic bitumen emulsions were used in road construction until the 1970s. The cationic bitumen emulsion has prevailed due to the problem of adhesion to the rock. Anionic bitumen emulsions are only used very rarely in road construction. Bitumen emulsions are mainly used as a bonding bridge in the layer composite when paving hot mixes and in the field of maintenance construction methods, especially surface treatments and " thin layers in cold paving " as binders. An important area of ​​application since 1988 has been the binding of pitch in recycled waste material with the addition of cement . This recycling material is mostly used in the substructure.

In the field of building protection, mostly anionic bitumen emulsions are processed into so-called thick coatings. These are mainly used to seal building areas that are exposed to pressing or non-pressing groundwater . Newly developed thick coatings have been made from cationic bitumen emulsions since the mid-1990s.