Precast concrete features strongly in the 1998-99 Concrete Society Awards. Fourteen certificates of excellence have been awarded in the Building and Civil Engineering categories, and the winners will be announced at the society's prestigious awards dinner on 12 November.
The shortlisted structures cover a wide range of structural types, and the applications of precast concrete are equally diverse, from straightforward functional use of precast beams and flooring units, through to the high quality finishes.
One of these is the reconstructed Portland stone elements on the new Brown & Root headquarters building at Leatherhead, for which the Marble Mosaic Company was the specialist supplier. Instead of being broken up into 'look-alike' ashlar units, the large cladding elements span from floor to floor, with joints between elements being emphasised and carefully oriented to control water flow over the surface.
A striking application of precast prestressed concrete can be seen in the A-frame sign gantries which receive a certificate of excellence in the Civil Engineering category. These are now being used across major roads and motorways, most notably on the A1(M) widening at Alconbury, where 40 have been used, and on the A1 M1 link south of Leeds, with 90 gantries. They were designed and developed by the Prestressed Concrete Association, and range in span from 14m to 37m, using C60 concrete.
The new acoustic wave wall barrier at Gatwick Airport, which also receives a certificate of excellence in the Civil Engineering category, represents an outstanding use of concrete in providing the right solution for the client's needs. Optimisation of unit design and 'just-in-time' delivery and erection minimised disruption during construction. Imaginative engineering, combined with careful choice of materials and high production standards, provides an attractive structure. More than 11m high and 430m long, the wall was designed to protect nearby residents from aircraft noise. It has also received a high commendation in the British Construction Industry Awards.
Conceptual design was by structural and civil engineer Anthony Hunt Associates, with precast concrete designer and manufacturer CV Buchan providing two key elements: first, making up the wall from 43 independent cantilevered wall sections tied together vertically; and second, match casting as an economic and effective way of building the 344 units, each weighing just under 12t.
Key characteristics which led to the choice of precast concrete were:
off-site fabrication and 'just-in-time' delivery allowed construction of the wall straight from the lorry, minimising construction space;
colour effects required by the architect could be readily achieved;
good acoustic properties;
allowed use of match casting and repeatable moulds.
Details from the Concrete Society, tel: (01753) 693313