Freeman Interchange

The ramp bridge is a five span, three lane post-tensioned concrete structure with a total length of 245 m. Some years after completion of the bridge cracking was noted on the south side of the east span. Brown & Co. was retained by Hwy 407 ETR to investigate the cause of cracking on the side face of the ramp structure and to design remedial measures.
Brown & Co. were able to determine that the cause of the cracking was a deep seated delamination centred on the lower post tensioning duct. Further examination of the grout material confirmed that the grout was frost susceptible and had high moisture content. The cause of the cracking was determined to be freezing expansion of the duct. Investigation along the full length of the sides of the bridge and internal cell did not reveal any other locations of delamination suggesting a limited deficient grout preparation resulted in the observed damage. The selected remediation included stage by stage exposure, removal and replacement of the grout, replacement of the delaminated concrete.
407 ETR
Investigation of existing conditions | Concept Design | Detailed Design | Tender preparation | Audit review of construction