Title:
Prediction and Control of Early-Age Cracking: Experiences From the Oresund Tunnel
Author(s):
S. Lykke, E. Skotting, and U. Kjaer
Publication:
Concrete International
Volume:
22
Issue:
9
Appears on pages(s):
61-65
Keywords:
DOI:
Date:
9/1/2000
Abstract:
The 16 km (9.9 mile) long Øresund Link, which opened on July 1, 2000, connects Denmark with Sweden by an immersed tunnel and a long bridge. A 100 year service life was specified — double that normally assumed by the Danish Code of Practice. The tunnel was designed to be watertight without external lining or insulation, and as a result connects the contract required that no early-age cracks be permitted in water-retaining portions of the structure. To prevent cracking, requirements for temperature differences and calculated crack risks were strict. Each concrete tunnel segment was cast in a novel way: inside a factory in a 2700 m3 (3532 yd3) placement. Due to this casting method, internal cooling during hardening was not required and no early-age cracking occurred. Cracking occurred in the ramp and portal structures, however, which were cast in-place and required internal cooling. An analysis of 350 wall castings revealed that about 100 cracked; of those, 40 complied with the requirements to temperature difference but not necessarily to crack risk. Overall, a fairly good correlation was found between predicted and achieved temperature difference, crack risk, and actual cracking.