Building Research Establishment

1998 Structural Survey  
The Building Research Establishment have been involved in two different types of pressure extension tests. In this paper the two groups of results have been brought together, and the effect of both on future designs of protective measures for new buildings considered. In one study the pressure field due to a central sump has been measured at many points within the fill below the floor slab. using tubes laid before the concrete floor was poured. These tests give detailed results for a small
more » ... ts for a small number of sites. This work was carried out with Cornwall County Council. In the other set pressure extension tests were carried out on the floors slabs of 78 newly built UK houses. The tests were carried out using holes drilled after the floor has been laid, so provide less data, but from more floors. The work was carried out by Wimpey Environmental Ltd, under contract to BRE. From the results we have greatly increased our understanding of how the type of fill material affects soil gas flow. There is considerable variation between results from sites which are supposed to be using similar fill materials. However with care very good pressure extensions can be achieved over large floor areas. In the UK there has been concern from builders about how to build on the recommended 'clean permeable fill*. These projects will help in the process of designing efficient, cost effective protective measures.
doi:10.1108/ss.1998.11016aab.001 fatcat:aqgnnwzdzrapneupcc6qkf776y