Road Asphalting Industry
The construction and repair of road surfaces constitutes the main outlet for bitumen/ asphalts and tars. Although the melting of such materials is a simple heating process that can utilise any fuel, they have characteristics that put a premium on the careful control of firing and the cleanliness of combustion gases.
In road construction, the aggregation of hot mixtures is facilitated by temperature adjustment immediately before spreading. Careful temperature controls assist this process. It is common practice to use LPG fired heating facilities in portable asphalt plants in order to heat bitumen before discharge into the mixers or spreading it on the road.
Bitumen is invariably melted on-site and therefore it is important to utilise fuels without smoky and malodorous emissions. The simple design of most bitumen melters also contributes to unsatisfactory combustion and this is why the use of a cleaner fuel is frequently the sole means of ensuring high quality results.
Furthermore solid bitumen is difficult to melt without bumping and sudden heat evolution. The materials are poor heat conductors and tend to melt or undergo local overheating long before the bulk of the pitch has softened. A well-controlled flame and good distribution of heat with no concentrated hot spots helps to avoid boiling, bumping and accidents due to spillage. In addition, the mixers themselves often have LPG burners to carry out final temperature adjustments.
Finally, portable LPG infra-red heaters can be used to heat sections of the road especially where road repairs are concerned. Using such equipment to melt and mend damaged road patches is significantly more economical than the alternative process (which is cutting out the road part with pneumatic drills and inserting a fresh hot mix into the hole). The bonded repair is not only cheaper but often much stronger than a patch inserted by cutting and filling.