Foundation systems: a new family of processes
"Up to now, professionals have been able to choose mainly from traditional underpinning techniques, for example such as the reinforcement of existing strip foundations or the construction of conventional deep foundations, explains Céline Florence, CSTB engineer.
The increase in requests for work on private homes and other small buildings has encouraged some contractors to innovate. They attempted to develop new, easier-to-use systems based on steel or aluminium micro piles with special geometries. For example, piles can be large single-thread or multi-thread- screws placed in the soil using lightweight hydraulic equipment. The technologies are attractive because they do not require major excavations.
After the processes have been developed, they have to be validated by experts, and they have to be known and recognized by site managers and the different players in the construction industry. "We have investigated two requests for Technical Assessment on these processes for which the independent expert group has issued favourable opinions", continues Céline Florence.
These new systems thus broaden the family of foundation processes for which a Technical Assessment has been issued; this family was started at the beginning of the 2000s with fiber reinforced concrete strip footings and then extended to include slabs.
This investigation and information strategy used by the building profession goes in the right direction towards control over innovative processes and therefore an improved building quality. And the principle appears to have been emulated! "We have just issued two Technical Experimental Assessments on similar processes", confirms Céline Florence.
Technical Assessment and ATEx
A Technical Assessment provides information about products, systems and new equipment, for a defined use. In particular it states the extent to which the product or the system satisfies the current regulations, is suitable for use in practice, and is durable in service.
The Technical Experimental Assessment (ATEx) is a fast technical assessment procedure formulated by a group of experts on any product, system or equipment not yet covered by a Technical Assessment, so as to make it easier to take account of innovation in construction.