Trass Wall in Krufter Bachtal

Between 1627 and 1858 the tuff in the Krufter Bachtal was mined by underground blasting, which is evidenced by boreholes in the walls. The definition of the period is based on the following facts: The use of blasting technology in European mining was first documented around 1627. Because of the dangers, underground tuff extraction was banned in 1858. For mining, a good 3 meter wide corridors were driven into the stone at a depth of about 15 meters. The distance between the aisles was about 20 to 40 meters. A rectangular underground tunnel system of approx. 250 m × 150 m was created. The blasting had already broken the tuff into smaller pieces. Crushed again by hand, the stones were stacked on arks for days. After a drying time of about 2 weeks, the stones were ground into fine rock powder, into trass. Trass has hydraulic properties and was used in conjunction with lime to create a waterproof mortar.