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24

www.concrete.org.uk

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concrete

ARCHITECTURE AND DESIGN

Brickpanels

Early on, there were some critical areas of

large brick panels that had to be installed

above the main arcades. As access had to be

from the arcade itself before the subsequent

roof structure could be installed, this was

all carried out to the required programme

and provided early enclosure to the rear

of the casino, at the same time releasing

following trades. The entire project, which

also included the adjacent John Lewis

Partnership store, was opened on 16 October

2016, with project architect ACME receiving

widespread critical acclaim.

One of the key issues faced was sourcing

appropriate brick material, first to meet the

architectural and planning requirements for

the Old Victorian quarter of the city and

second, and equally importantly, to satisfy

the necessary technical characteristics to

cope with a high degree of exposure to

the elements over time.With most brick

manufacturers only willing to guarantee one

stretcher face and one good header, Thorp

needed to find suppliers willing to guarantee

all faces, in particular the exposed projecting

brick on bed faces.

Once the choice had been narrowed down

to two potential brick types, small mock-up

panels were cast featuring the projecting

brickwork detailing and factory pointing

with the preferred mortar colour and joint

profile. These were then dispatched to an

independent test laboratory to undergo

rigorous freeze–thaw cycles and pull-off tests.

As a result, a UK-manufactured

Staffordshire Smooth Red facing brick was

finally selected.Not only did these prove

entirely fit for purpose but the extruded

method used in their manufacture allowed

Thorp to develop a special positive key for

casting purposes, specifically designed to

minimise any cutting and make full use of

each individual brick unit, producing two

suitably keyed snap headers, with barely

any waste.With durability and long life in

mind, it is also worth noting that the panels

were specifically designed to prevent pigeons

roosting on the exposed decorative brickwork

ledges, the panel geometry being cleverly

devised to avoid this possibility.

The usual logic when using precast

cladding in large volumes is to make good

use of as much repetition as possible. In

this case, however, very few cladding panels

were duplicated across the scheme. As a

consequence, Thorp was unable to use

traditional mould materials such as timber,

metal or glass-reinforced plastic because the

cost of making so many individual moulds

to cast the dozens of different panels would

have been prohibitive. Instead, the key was

to find a low-cost sacrificial material with

the flexibility to create all the various profiles

required. And here the company came up

with the idea of creating a series of profiled

formers from polystyrene, using computer-

generated hot-wire cutting machinery,

which were not only cost-effective but robust

enough to be used several times over.

Toblerone

Above the glass roof of the shopping arcade,

supported by the primary steelwork frame,

there are some much simpler large spanning

flat brickwork panels along with some curved

brickwork elevations that required radial

moulds. All these were produced in timber

moulds made in the conventional way. At

lower level, retail areas are distinguished by

smoother black precast concrete cladding

panels, with a highly polished exposed

aggregates surface finish. These are in stark

contrast to the slender, angular, terracotta and

recon stone ‘Toblerone’ fins fully integrated

with the three-dimensional brickwork

patterns on the upper floor. Some of these

combine two, or all three,materials in the

same large spanning panels.

In some cases, the terracotta and

reconstituted stone elements needed to be

manufactured separately, then placed in the

primary mould with projecting reinforcement

to act as permanent formwork for casting

integrally with the pleated brickwork. The

interface junctions where all these materials

are carefully aligned provide a seamless

transition between all the various elements.

The Hammerson Victoria Gate Arcade is

another outstanding example of how modern

methods of construction bring significant

value to any project, with a quality of finish

exceeding all expectations.

The adjacent John Lewis

store façade.

(Photo:ACME Architects.)