Alpine Bau GmbH has built an asphalt-mixing plant equipped with state-of-the-art, environmentally friendly technology on the site formerly occupied by chemical industry facilities. The plant's construction has called for an investment of six million euro.

All sorts of special asphalts can be produced at this new plant, using cutting-edge technology. The plant's location, very close to the A7 and A1 motorways, makes it possible to supply the city of Linz and the district of Mühlviertel without having to cover long distances.

Step-by-step asphalt production

When gravel reaches the plant, it is stored in silos having a total capacity of over 7,000 tonnes. Afterwards the gravel is conveyed to the drying drums, where it is dried at approximately 200 °C. Next it is transported to the screening machine and from there to a bucket conveyor. After screening, the gravel is distributed into 12 different containers, depending on grain size.

To make asphalt, the gravel is added to the mixer, depending on the required composition. Bitumen is injected and is mixed with the gravel for about 40 seconds. Afterwards the mixture is loaded onto lorries that are covered with a tarp, or it is driven to the site in "thermo trucks".

The accumulated dust and bitumen vapours are eliminated via a comprehensive exhaust system equipped with filters, and they are recycled. In addition, the plant is completely enclosed to reduce sound emission. In order not to tax natural resources, recycled asphalt (i.e., asphalt obtained by digging up old asphalt from roads and crushing it) is used in production.

The plant has the capacity to manufacture up to 240 tonnes of asphalt per hour, and the energy it burns is supplied by natural gas. Asphalt is a mixture of mineral aggregate in which petroleum bitumen acts as a binder, in a proportion of 93-96% aggregate to 4-7% binder.