Assessment of Creep and Shrinkage of Concrete for the Flintshire Bridge

In order to control the alignment and stresses of the Flintshire Bridge, accurate long-term creep and shrinkage data were required for analysis by a finite element model. Since the concrete contained mineral and chemical admixtures, the design model of BS 5400: Part 4 was deemed to be inappropriate, as the creep and shrinkage factors apply for admixture-free concrete. Consequently, laboratory tests were undertaken in which specimens were loaded at ages corresponding to the prestressing and tensioning operations of the bridge segments. Elasticity, creep and shrinkage were measured over a period of 1 year and compared with values estimated by five methods of prediction. The methods were then used to extrapolate the l-year laboratory results to equivalent 50-year deformations of the bridge segment and to estimate the halffinal deformation times and the eflects of a change in mix proportions on creep and shrinkage.

J.J. Brooke and H. Al-Qarra