Bitumen emulsions must never be heated above 90°C, and must be protected from freezing. Above 90°C there is a risk of boiling and hazardous spillage through vigorous frothing, and prolonged heating even below that temperature can damage the emulsion and change how it behaves on the road.
Road Emulsion Association, Technical Data Sheet No.2
What is being stored
Bitumen road emulsions are water based road construction products in which the dispersed phase is bitumen. Bitumen itself is virtually involatile, adhesive and waterproofing, derived from crude petroleum, and very viscous or nearly solid at ambient temperature.
It is emulsified in water using surface active additives and other chemicals to decrease its viscosity, so that it can be applied at a lower temperature than would otherwise be possible. On application the water phase is removed naturally, by absorption into the road surface or by evaporation, leaving the residual bituminous binder behind.
Temperature: the limits that matter
Depending on the particular use, emulsions may be applied at various temperatures above freezing, from ambient, where there is no additional hazard due to temperature, up to a maximum of 90°C.
Emulsions should never be heated above 90°C to avoid the possibility of boiling and hazardous spillage due to vigorous frothing.
REA Technical Data Sheet No.2
Heating in excess of 90°C, or for prolonged periods at lower temperature, can damage emulsions and change their application properties. Emulsions should equally be protected from freezing, which damages them too.
There is a separate and serious hazard where emulsion meets hot bitumen. If emulsions come into contact with bitumen above 100°C, there is a significant risk of spillage caused by rapid expansion of the boiling mixture.
Safety, health and environment
Bitumen in service as a road surfacing material is not known to present any safety, health or environmental hazard, and its use for that purpose is permitted and registered under chemical safety legislation.
One point on first aid is worth knowing before it is needed: no attempt should be made to remove cold bitumen that has adhered to the skin, unless circulation is impeded. Medical advice should be sought.
Transport
The Chemical Industries Association ‘Black and White’ marking scheme advice should be followed when signing delivery vehicles, mobile storage tanks and mobile application plant.
Storage in bulk
The Road Emulsion Association publishes a Code of Good Practice for the Use and Safety of Mobile Storage Tanks, and the advice in that publication should be followed, particularly on siting, receipt of deliveries and heating.
Storage in drums and packs
Bitumen emulsions have a limited shelf life, which depends on the specific formulation and on storage conditions. It is important to rotate stock so that older drums and packs are used first.
Waste disposal
Depending on the formulation, bitumen emulsions and the containers they have been stored in may be classified as either non-hazardous or hazardous waste. Both must be disposed of in compliance with the relevant legislation.
Related
All REA technical datasheets — twelve datasheets covering emulsion types, handling, surface dressing, bond coating and more.
The REA also publishes a Code of Good Practice for the Use and Safety of Mobile Storage Tanks, referenced throughout this datasheet.