Pyrometer in the process of the mixture of asphalt

In asphalt mixing plants and asphalt mixing works, concrete is produced by a thermical mixing process.  In this mixing process the mineral stones, fillers (rock flour) binding agents (mostly bitumen) and if necessary additives, are processed in a heat process (Wikipedia asphalt mixing plants, 14.11.2016). At the end of the mixing process, the temperature of the concrete is measured, usually with a stationary pyrometer which can steadily withstand the harsh environmental conditions.