MANUFACTURING

The page on this site "What is mastic asphalt" has shown that three major components are needed:- Bitumen, Filler and Aggregates. The manufacturing of mastic asphalt is based on the need to heat these three components, mix them thoroughly, and ultimately transport the mixture to the installation site.

There are two principal methods used for the manufacturing - the older traditional method, and the newer continuous process.

OLDER TRADITIONAL MIXING. The selected raw materials are simply placed in a large heater mixer, with capacities up to around 20 tonnes of hot mix. External burners simply heat this "cooker", which has internal mixing paddles to slowly agitate the mix as it is heated. Several hours later the whole mix will have reached the right temperature and will be ready to discharge. The mix may be transferred to "hot-charge" tankers which can transport the hot mix to the installtion site, or cast into large molds, each holding 10-25 kg of mix, and allowed to cool. This will produce mastic asphalt blocks which van be transported to site and remelted in small heated mixers, very useful for smaller jobs.

MODERN CONTINUOUS MASTIC ASPHALT PRODUCTION

The photo shows Rock Asphalte's  modern mastic asphalt production plant at Elstow  Bedfordshire. The process: The raw materials are heated separately. Larger aggregates and grit in an efficient drum dryer. Filler is heated in a stirred tank with external heaters. Bitumen is supplied by tanker, arriving hot, and stored in heated and insulated tanks. The components are fed by computer control to a twin paddle pugmill (mixer) in one tonne batches. Mixing is rapid, with one tonnne batches every 45 seconds which drop into the hot charge transporters, ready for delivery to the installation sites.