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concrete

43

FIBRES

to the complex and potentially dangerous

restoration of a coastal slipway.

East Devon District Council (EDDC)

has recently funded the £1.2mMamhead

Slipway project in Exmouth to reopen

maritime access to the River Exe, in the hope

of increasing visitor numbers to the area;

the original structure was closed in 2012

and eventually demolished by contractor

Raymond Brown Construction as part of the

rebuilding process.

Following Environment Agency guidance

– which stipulates minimal use of traditional

steel reinforcement where practicable in

marine and coastal concrete – EDDC,

in conjunction with the contractor and

structural engineer, used SikaFiber Force 400

to help extend the service life of the slipway

and provide a safer, cost-effective and high-

performance alternative to traditional steel

reinforcement. The product is manufactured

from 100% virgin homopolymer

polypropylene monofilament fibres, which

contain no reprocessed olefin materials and

comply with BS EN 14889-2

(1)

.

The system enhances the toughness

of concrete, removing the need for steel

reinforcement, when used in appropriate

situations. Simple to apply, as well as

being easier and safer to handle than steel,

the product offers a three-dimensional

reinforcement solution that does not rust or

corrode when exposed long term to chlorides

in seawater.

Due to water level and tidal fluctuations,

Mamhead Slipway works took place behind

a cofferdam provided by interlocking sheet

piles. This resulted in a highly restricted

working area with mobile plant operating

alongside site operatives.However, significant

health and safety hazards for the workforce

were eliminated, due to the availability of

macro-synthetic fibres.Had welded steel

fabric reinforcement been specified, a crane

would have been required to lift it into

position, leading to potential disruption for

drivers and pedestrians, as well as causing a

danger for on-site construction teams and a

potentially increased programme time.

Mamhead Slipway

construction.

Placing traditional steel fabric reinforcement is a labour-

intensive operation, as it is often difficult to determine

whether the fabric has been placed correctly within the slab.

Reference:

1. BRITISH STANDARDS INSTITUTION, BS EN 14889.

Fibresforconcrete.Part2–Polymerfibres.Definitions,

specificationsandconformity

. BSI, London, 2006.

Futureproof attraction

Using SikaFiber Force 400 allowed the

concrete to be poured directly into the

slipway’s formwork, thus ensuring the

reinforcement’s containment within

the delivered concrete and resulting in a

more efficient installation and reduced

construction time.

The slipway’s six-month construction

programme was completed in September

2016. The 38m-long × 12m-wide feature

was described by Exmouth Regeneration

Board chairman, Cllr Philip Skinner, as a

“larger, safer and more resilient facility for

people to use for decades to come”.

For any system to retain its relevance to the

times, it has to evolve. Potentially,macro fibres

can be applied in precast and sprayed concrete

solutions, as well as traditional, vertical

concrete walls and piling, adding to the theory

that the macro-fibre age is here to stay.