BS 8110's definitions of surface finish are purely descriptive, and subjective. No physical references are available. As a result, there are often conflicting views between the client and members of the project team over whether a completed structural concrete finish is the one that has been specified. A new project aims to provide a series of reference panels that offers a physical and visual benchmark of structural concrete finishes and so allow all parties to agree on an acceptable standard of finish both before and after the concrete is poured.
The 50,000 project is being undertaken by CONSTRUCT, the Concrete Structures Group, with 50% funding from the Department of the Environment, Transport and the Regions. It involves the definition and manufacture of panels which interpret standard concrete finishes to BS8110. Reference panels have now been installed at seven locations throughout the UK.
For the first phase of the project, CONSTRUCT has concentrated on surface finishes A and B as these are the two most widely used. Demonstration panels are 3m high by 1m wide and are 250mm thick to depict typical storey height construction.
The specification for the Type A finish calls for untreated ply formwork. For Type B the formwork is paper-faced ply. All the panels were made using grade C35 concrete with reinforcement, but at each of the seven sites local aggregates were used to create authentic samples.
There are differences concerning blemish size and colour variations. For Type A the allowable blemish size is 12mm, for Type B it is 8mm. Similarly, less colour variation is acceptable for Type A compared with Type B. The panels were manufactured under the control and supervision of John Doyle Construction, a major specialist concrete contractor and member of CONSTRUCT.
Location of the reference panels has been determined by ease of access, range of viewing distance and availability of natural light. Internal locations were preferred to minimise weathering.
The reference panels feature prominently in the National Concrete Frame Specification, a performance- based document on best practice launched earlier this year, and will also be the subject of a joint publication by CONSTRUCT and the Concrete Society. Each site location also has copies of an explanatory manual giving an assessment of each panel, materials and manufacturing details, design criteria and specification.
The reference panels are located at: London (south): University of Greenwich, Oakfield Lane, Dartford, Kent DA1 2SZ. Contact Terry Graves, tel: (0181) 331 9377.
London (north): John Doyle Construction, Little Burrow, Welwyn Garden City, Hertfordshire. Contact Eric Roberts, tel: (01707) 239 481.
West: University of West of England, Faculty of Built Environment, Frenchay Campus, Coldharbour Lane, Bristol, Avon BS16 1QY. Contact Brian Dury, tel: (011)7 965 6261 ext 3060.
Midlands: Peri, Market Harborough Road, Clifton upon Dunsmore, Rugby, Warwickshire CV23 0AN. Contact Tim Pope, tel: (01788) 861 600.
North West: UMIST, Department of Civil and Structural Engineering, Sackville Street, Manchester M60 1QD. Contact Paul Nedwell, tel: (0161) 200 4613.
North: University of Sheffield Centre for Cement & Concrete, Mappin Street, Sheffield S1 4DU. Contact Roger Crouch, tel: (0114) 222 5716.
Scotland: University of Paisley, High Street, Paisley PA1 2BE. Contact Bill Matthews, tel: (0141) 848 3280.
Colin Cleverley is executive secretary of CONSTRUCT