Method for connecting precast segments tendon ducts and resulting structure

Abstract

A method for establishing an air-tight connection between post-tensioning tendon ducts of two consecutive precast segments of a structure, each segment being cast with a recess opening out on a jointing face of the segment leaving an access to ends of the ducts. The method including connecting pairs of respective duct ends of the two consecutive segments together, and pouring a sealing material into the recesses of the two consecutive segments around the duct ends while preventing the material to enter the internal space of the ducts, thus forming an air-tight connection at the junction of ducts.

1 . A method for establishing an air-tight connection between post-tensioning tendon ducts of two consecutive precast segments of a structure, each segment being cast with a recess opening out on a jointing face of the segment leaving an access to ends of the ducts, the method comprising:
 a) connecting pairs of respective duct ends of the two consecutive segments together, and   b) pouring a sealing material into the recesses of the two consecutive segments around the duct ends while preventing the material to enter the internal space of the ducts, thus forming an air-tight connection at the junction of ducts.   
     
     
         2 . The method according to  claim 1 , wherein the sealing material is Ultra High Performance Fibre Reinforced Concrete (UHPFRC). 
     
     
         3 . The method of  claim 1 , the segments being deprived of reinforcement bars protruding out into the recesses. 
     
     
         4 . The method of  claim 1 , wherein a thermo-retractable sleeve is pre-fixed on one of the duct ends of a pair of ducts and then the sleeve is slid over and sealed onto the pair of ducts. 
     
     
         5 . The method of  claim 1 , wherein an inflatable tube or an inflatable ball, is introduced into the ducts and inflated before the sealing material is poured so as to seal the inner part of the joint between ducts. 
     
     
         6 . The method of  claim 1 , wherein step b) takes place concurrently with tendon threading. 
     
     
         7 . The method of  claim 1 , wherein the recesses are provided in a lower or upper slab of the segments and open out into the top surface of the said lower or upper slab. 
     
     
         8 . The method of  claim 7 , wherein the recesses are adjacent the lateral walls of the segments. 
     
     
         9 . The method of  claim 1 , wherein the segments are made using match casting. 
     
     
         10 . The method of  claim 1 , wherein the segments are box segments. 
     
     
         11 . The method of  claim 1 , further comprising testing the air-tightness of the connection of the ducts. 
     
     
         12 . A method for casting a segment, comprising:
 c) Positioning in a mould:
 ducts for the passage of tensioning tendons, 
 inserts for making recesses into which the ends of the ducts extend, 
 reinforcing bars, and 
   d) pouring concrete in the mould.   
     
     
         13 . The method according to  claim 12 , wherein the reinforcing bars are curtailed so as not to extend within the recesses. 
     
     
         14 . A method for building a segmental structure comprising assembling precast segments in continuity of each other, each segment comprising post-tensioning tendon ducts, the method comprising implementing the method of  claim 1  for connecting the ducts. 
     
     
         15 . A segmental structure made in accordance with  claim 14 , the segmental structure comprising a bridge deck having at least two precast segments incorporating ducts in which tensioning tendons are threaded, the ducts being connected together at the joint of the segments by at least one block of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) extending around duct ends of the two adjacent segments, this block extending into adjacent recesses of the segments opening out on a jointing face of the segments.