Hanson cement replacement product enhancing concrete durability in new flood-defence scheme
HANSON’s Regen GGBS (ground granulated blast-furnace slag) cement replacement product is enhancing the durability of the concrete used to construct a new tidal barrier across the New Cut river in Ipswich.
The £21 million project for the Environment Agency will protect around 2,000 properties that are at risk of flooding in the town. The work is being carried out by VBA, a joint venture between VolkerStevin, Boskalis Westminster and Atkins, and the barrier is due to be fully operational by September this year.
Almost 5,000 cubic metres of concrete, containing up to 70% Regen, has been used to construct the 20m wide barrier gate and piled flood-defence walls. Concrete containing Regen has a finer pore structure, reducing its permeability and making it more chemically stable and resistant to sulfate and chloride attack.
The main barrier structure also required a low-heat concrete due to the scale of some of the pours, which were up to 730 cubic metres. Using Regen GGBS in the mix reduced the heat of hydration, protecting the structure from early-age thermal cracking.
‘Regen GGBS is ideal for projects that require the concrete to withstand aggressive environments,’ said Hanson Cement technical development manager Robin Styles.
‘And, it offers the added benefit of sustainability: Regen is manufactured from a by-product of the iron making industry and using it to replace one tonne of Portland cement reduces the embodied CO2 of the concrete by around 850kg.’