Tucked away towards the rear of the massive Cardington building, somewhat overshadowed by the European Concrete Building Project's new insitu framed structure, a smaller test programme is reaching its final stages.
Small it may be by comparison to other projects at Cardington, but the SINSLAB research being undertaken by the BRE's Centre for Concrete Construction promises equally innovative results.
Centre director Dr Stuart Matthews explains: 'Basically SINSLAB is a development of the floor construction used for the BRE's environmentally- friendly office building, which was opened last year. We're taking the concept out to much longer spans, and developing a simplified design approach.'
SINSLAB is aimed at the naturally-ventilated building sector. To form a floor slab with an internal ventilation duct, thin curved precast concrete soffit shells are stitched together longitudinally and transversely with the revolutionary Danish-developed Densit high strength concrete 'glue' (see box). Insitu concrete is poured around timber void formers. The shells have cutouts to allow cold air drawn in from outside the building to flow into the room below - and to function effectively, these cutouts must be near centre span.
'We tested SINSLAB at 14m span with a load of 7.5kN/m2', Matthews reports. 'Deflection was only 14mm - 1 in 1,000.'
He adds that construction of the test slab was straightforward, despite the unusual features of the design. 'The Densit worked like a dream, although it did mean making a large number of small mixes. But no specialist labour was needed. It was all built by the normal BRE team.'
Ultimate load tests have just been completed. A dozen jacks simulated a load of 35kN/m2 - seven times the design service load - under which the SINSLAB deflected 70mm at mid-span. Even then damage was limited to flexural cracking - an amazing result, Matthews says.
Projects like these are just one aspect of activities of the centre, which took on its current identity when the BRE was privatised last year. Matthews moved to Watford in 1992 as head of the structural appraisal and monitoring section of the then BRE's structural performance division. Before that he had several years as managing director of the materials and building maintenance division of Travers Morgan, which followed five years with Structure Testing Services (UK).
Matthews became director of the centre earlier this year, combining the responsibility with that of director of the Centre for Repair & Refurbishment, a post he took up in 1997. He says this dual role is more logical than it may seem at first glance.
'Since privatisation, BRE has been organised on a matrix basis, which enables us to offer a very broad-based service. My responsibilities reflect the fact that a lot of the enquiries the Centre for Concrete Construction receives involve durability problems and what to do about them.'
Marketing the BRE's services on a centre by centre basis does make it simpler for potential customers to focus their enquiries, Matthews acknowledges. Already the concrete centre is actively recruiting more technical staff, and hopes for the future are high.
'We see a number of potential growth areas, not all of them to do with durability problems,' he says. 'Improving the construction process through projects like SINSLAB, long term in-service building monitoring, non-destructive testing, there are almost too many opportunities and challenges.'
He sees no reason why the new BRE should be largely confined to the building sector. Proposals on the long term monitoring of highways structures are under development, and work is in progress on the degradation of materials in aggressive environments which will have an impact on all sections of the construction industry. It was to the BRE that highways engineers turned recently when the thaumasite form of sulphate attack was discovered on bridges crossing the M5.
At the moment, what Matthews describes as 'technical consultancy and collobarative research' makes up only about 10% and 15% of the centre's business. In the longer term he expects private commercial research to help this to increase to something more like 30%. Some might see this as running counter to the old BRE's culture of disseminating its research results as soon as possible to the whole industry, but Matthews foresees no real problem with commercial confidentiality - or with potential commercial customers' appreciation of the BRE's new role. 'Clients do now appreciate the need to pay for our services,' he says.
As for competition, Matthews believes it will come from 'everyone and no-one'. He explains: 'Because of the breadth of the services we
can offer, BRE actually competes with practically every other test house, research organisation and university department in the country. Which means that no-one can match that breadth of service in practice.'