From Waterways to Roads -
Development Outline of the Rhineland Basalt Industry in the 19th and 20th Centuries
Basalt, an igneous volcanic rock, has been much in demand in the construction industry for millenniums, in particular for the construction of transportation routes. As other natural stones, basalt was and still is almost exclusively quarried from above-ground deposits; in Germany, for example, from deposits located in the Middle Rhine area and the Westerwald. A closer look into the history of the basalt industry - using the basalt industry in the German Rhineland as an example - is extremely rewarding, also in the context of the region's coal mining and steel history. Interesting elements include production technologies and the sales potential which infrastructure constructed with basalt opened up for coal and steel products (e.g. railways, harbours).
Basalt has gained its great importance as a material in transportation route construction thanks to its excellent properties. Its high value is due, above all, to its outstanding hardness and durability which are clearly better than for most other natural stones. These properties derive from the specific formation process and chemical composition of basalt, which also make it highly resistant to weathering. Other properties still important today include its high specific weight and, above all, its enormous resistance to pressure. Depending on the type of deposit, one square centimetre of basalt can resist a pressure of more than two tonnes, in some cases even considerably more. Its specific formation process often produced basalt columns which were five- to seven-sided and closely clustered, so-called columnar basalt. Other deposits consist of block or slab basalt. While block and slab basalts were mainly used to produce paving stones for the construction of roads, columnar basalts were found suitable for reinforcement measures, for both military fortifications and the reinforcement of shores and banks. Following a review of the pre-industrial use of basalt in general, the article focuses more specifically on columnar basalts as their use as a construction material is a speciality in the basalt industry.