Experimental weathering of marlstone from P ední Kopanina (Czech Republic)—historical building stone of Prague

Romanesque builders favoured marlstones because of their easy workability. Unfortunately, this rock rapidly deteriorates when exposed to the external atmospheric conditions. Artificial weathering experiments were conducted on marlstone from P ední Kopanina quarry near Prague (Czech Republic) in order to determine: (A) which weathering factor presents major danger to this rock type, and (B) which of the test methods provide the most reliable measure of the intensity of rock disintegration. Rock specimens prepared from fresh rock were subjected to standardized freeze–thaw cycles and salt crystallization tests, and to the accelerated weathering in climatic chamber using SO2 and a combination of freeze–thaw and SO2 cycles. Stone properties were evaluated by non-destructive and destructive techniques including ultrasonic velocity measurements, determination of water uptake by capillary action, mechanical testing, detailed porosimetric analysis and microscopic study.