Bonded Strand Post-Tensioning System
Metal ducts represent the most economical means to create a void for tensile elements. These thin-walled (0.25 - 0.60 mm), ribbed sheet metal ducts provide a fair secondary corrosion protection with excellent bond behavior between tendon and concrete. Primary corrosion protection is provided by the alkalinity of grout and concrete.
The tendon type number (e.g. 5901, 6801) is composed as follows:
- the first digit (5 or 6) identifies the nominal strand diameter in tenth of inches, i.e. 0.5" or 0.6"/ 0.62",
- the last two digits (..01) reference the number of used strands (= 1 strand)
- The second digit is an internal code
As regards the 0.6" tendon types, the accessories fit both Grade 250 (GUTS 1770 N/mm2) and Grade 270 (GUTS 1860 N/mm2) strands.
PE/PP Round Duct
Thick-walled polyethylene/polypropylene plastic ducts provide long-term secondary corrosion protection especially in aggressive environments such as in the case of waste water treatment plants, acid tanks, silos or structures exposed to de-icing salts.
DYWIDAG-Systems International offers polyethylene/polypropylene ducts in straight lengths up to ~24 m for all sizes. Standard shipping length is ~12 m. Longer lengths in coils are available for all sizes except 130 mm.