BAM Ritchies: NAB Tower, English Channel
Nab Tower is situated in the English Channel approximately eight miles from the coast at Portsmouth, guiding shipping into the deep water channel approaches to the Solent and Southampton. After almost a century out at sea, the tower was showing signs of wear and tear, with the outer steel casing rusting and perforated. As part of its reconstruction, the steel casing of the tower was removed to expose the inner concrete core.
BAM Ritchies team, travelling the 45 minutes by boat from shore, cleaned the core by grit blasting and applied a 75mm layer of Fosroc’s Renderoc DS sprayed concrete material from an access cradle suspended from a tower crane erected within the tower’s core. As part of the plan to provide long term corrosion resistance for the sprayed concrete overlay, stainless steel ‘L’ shaped dowels were used to mechanically secure the sprayed concrete to the tower core and 20mm long stainless steel fibres were incorporated in the sprayed concrete mix to provide crack resistance.