The Thio Material shaft units wholly answer to strength class 60. The unreinforced cover slab meets the requirement of 300 kN crushing strength according to PTV 823. The unarmoured tubes conform to strength class 160 in accordance with PTV 823 (vitrified clay pipes strength class 160  – concrete: strength class 250).

• Tested in accordance with: NBN EN 1917 and NBN EN 1916