Other uses of bitumen emulsion

A plain English summary of REA Technical Data Sheet No.12, revised by the Association’s Technical Committee in August 2025. The datasheet is the authority; this page exists so the guidance can be read, searched and quoted without opening a PDF.

Asphalt preservation

The service life of a bituminous surface course suffering from oxidation can be extended economically by applying a proprietary preservation emulsion at the right time. These modified emulsions are formulated at low viscosity so they penetrate cracks and interstices, sealing and waterproofing the surface with minimal effect on texture depth, and leaving a tack free surface. Application is normally by spray tanker on carriageways and car parks, and by hand on footpaths and driveways. Rates come from the individual suppliers.

Joints in pavement courses

Stable, watertight joints matter to the long term performance of a flexible pavement: they keep water out of the structure and reduce the risk of fretting along the joint. The Specification for Highway Works, clause 903, recognises that cold applied bitumen emulsions can be used instead of hot bitumen to coat the vertical face of longitudinal and transverse joints in surface courses, and that polymer modified emulsions can be applied as a surface seal over them.

The advantages of the cold applied product are practical ones:

• No heat, so less plant and less fuel.
• Safe and easy application, with the hazards of hot material removed.
• Small areas can be dealt with at once, without waiting for a bitumen heater to warm up.
• Easier transport, without waiting for the heater to cool down before it is moved.

Specially formulated emulsions for joint painting are firmly established in the UK.

Filling surface cracks

Polymer modified bitumen emulsion is an effective material for sealing cracks in pavement surfaces, and it allows prompt corrective action before moisture and detritus reach the structure underneath. A number of emulsion based compounds are available with the skid resistance needed for use on a public highway.

Protecting buried concrete and ironwork

Emulsions are used to protect exposed and buried concrete and ironwork. Polymer modified emulsion is normally chosen, to give the material more body and a stronger surface film.

Slip coats

A bitumen membrane between the base and the upper layers of a concrete slab pavement stops rigid adhesion between layers of different ages and strengths, so each can mature without setting up internal stresses. It also helps the lower layer keep its strength, by preventing water seeping in through cracks.

Grades C60B3 or C60BF3 are preferred, applied either in one application at about 1.8 litres per square metre or in two at about 0.9. Two applications carry an extra benefit: the first can act as a curing agent for the lower layer, provided it is allowed to break completely before the second goes on.

Colour and surface seals

Mixtures of fine aggregate and bitumen emulsion can be applied to asphalt or macadam as a surface seal, and ready mixed slurries are available in colours including grey, red and green. Several coats may be applied depending on the traffic. These materials are normally applied at paint film thickness and are not very resistant to abrasive trafficking and scuffing, but they are an economical and colourful way of sealing paved surfaces in low traffic areas where colour definition and surface renovation are wanted.

Surface dressing encapsulation

New and existing surface dressings can be treated with proprietary encapsulation emulsions, formulated to lock in the aggregate, reducing or preventing chipping loss and improving the stability of the dressing in stress areas.

On an older dressing, these sealcoats arrest the effects of oxidation, reduce chipping loss and reseal the surface with minimal effect on the existing texture depth. They also give a uniform black appearance similar to a conventional surface course, which can be particularly useful in urban residential areas where surface dressing might otherwise be thought unacceptable.

Skid pans

A surface suitable for skid testing is made by depositing a film of hard bitumen on a smooth surface, which a specialised hard grade of emulsion does simply enough. Sprayed evenly, it dries to a hard, shiny surface with low resistance to skidding, and it can be sprayed again when it loses its smooth texture with use.

Stabilising blowing sand

Sand dunes and similar areas often need treatment to stop the surface eroding in the wind. An emulsion stabilises the surface to a depth of about 40mm while still allowing drainage. Grade C55B4 or C55BF4 is the usual choice, diluted with three to four times its volume of potable water and applied at between 8.5 and 11.0 litres per square metre. Take care not to leave surplus bitumen on the surface.

Hydroseeding and grass growth

On new road construction, grass needs to root quickly to stabilise slopes and soiled areas. A bitumen emulsion layer over the seed bed helps in three ways: it prevents water evaporating from the surface and keeps the soil moist; the black layer absorbs heat during the day and releases it slowly at night, creating conditions that encourage germination; and the seed bed is less likely to become waterlogged, blown or washed away, or eaten by birds.

An accepted method is:

1. Prepare the seed bed as normal to a fine tilth, apply a good grass seed mixture at the recommended rate, roll lightly and water if necessary.
2. Apply a layer of clean sharp sand evenly, about 5mm deep.
3. Apply grade C55B4 or C55BF4, or A1-55 or A1-60 to BS 434-1, at about 0.7 litres per square metre.
4. Cover the emulsion film with another layer of clean sharp sand, about 5mm and no more than 10mm, which prevents damage in the early stages of growth.

There are many other uses for bitumen emulsion in civil engineering and construction. REA member companies can advise on them.

Download Technical Data Sheet No.12 (PDF)Miscellaneous Uses of Bitumen Road Emulsions. Revised August 2025.