Sea defences pose one of the toughest of all challenges for the concrete technologist. Wave impact and constant abrasion from sand and shingle can soon degrade the cover to the structural steel, leading to the inevitable corrosion and spalling. So when main contractor Volker Stevin took on the £11M refurbishment of the sea defences between Ovingdean and Brighton Marina it turned to plastic fibre reinforcement for the solution.
The project involves the encasement of the old sea wall, renovation and encasement of existing groynes and reconstruction of the beach access steps and ramps, splashwall and promenade. More than 11,000m 3of fibre reinforced concrete will have been used by the time the project is complete next month - and the chosen fibre was ADFIL's Fibrin 23.
Each 18micron diameter polypropylene fibre is cut to a 12mm length.
ADFIL claims that its patented extrusion process can produce fibres up to three times finer than any other commercially available alternative.
1kg of Fibrin 23 contains 360M individual fibres, the mixes on this project use 0.91kg/m 3.Fibres in the mix reduce bleeding and segregation in the fresh concrete and have a beneficial affect on long term permeability.
Reduced permeability means greater durability and resistance to chloride ion penetration.
ADFIL claims that tests have shown Fibrin 23 fibres can increase the abrasion resistance of marine concrete by 25%, and boost its impact resistance by more than 400%.