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This paper deals with the investigation of properties of Czech fortification concrete bunkers built before Second World War (WWII). The Czech defense system consisted mainly of light bunkers type No. 37. The vast numbers of these bunkers have been preserved in various conditions to nowadays. The light bunkers type No. 37 were designed to last limited lifetime of decades. According to the preserved test protocols, strength of used concrete varied from 40 to 50 MPa, measured on cube specimens with dimensions 200×200×200 mm. The non-destructive analysis of compressive strength, determined by Schmidt hammer was performed. This method was used to maintain a historical value of the structures. Three were analyzed different bunkers type No. 37 located in Western Bohemia – Pilsner region. Tested bunkers are preserved in various conditions with various quality of concrete. The measurements by Schmidt hammer took place in several locations especially in the interior part. The exterior was also investigated but only in the locations of surface which were not covered with camouflage plaster. Nondestructive testing had shown high quality of concrete older than 80 years old concrete, with compressive strength between 50 to 60 MPa.

Properties of Czech WW2 Concrete Fortifications after 80 Years