Experimental study of crack initiation and crack damage stress thresholds as critical parameters influencing the durability of natural porous stone

01.01.2013 - 30.12.2016
Grant agency: 
Registration number: 
Internal investigator/coinvestigator: 
Tomáš Lokajíček
Interní řešitel: 
is coinvestigator
External investigator/coinvestigator: 
Univerzita Karlova v Praze, Akademie výtvarných umění v Praze, Ústav struktury a mechaniky hornin AV ČR, v. v. i.

The durability of natural stone is assumed to be intimately related to pre-peak fracture process (crack initiation and damage), which can be derived from stress-strain behaviour during compression and/or tension. Compared to previous empirical evaluation (freeze-thaw cycles, salt crystallization, hydric dilation) of the durability of natural stone, in this new project this will be resolved through experimental rock mechanical tests employing acoustic emission monitoring. Testing will include rock fabric analyses prior and after the tests on porous rocks (sandstones, silicites, tuffites, bioclastic limestones) showing variable porosity (5-30 vol. %), pore size distribution, granulometry, degree of cementation, and physical properties. Prior to the rock mechanical tests, certain specimens will be artificially weathered and/or consolidated in order to evaluate effect of rock fabric modification on the mechanical properties. From the stress-strain curves, energetic parameters of deformational process will be derived as a key factor influencing the durability of natural stone.