Lightweight Recoverable Foundations on Suitable Ground

One of the greatest challenges to be faced in the fight against climate change in the construction sector is the fact that (non-traditional) conventional solutions are routinely accepted despite their high environmental impact. In particular, reinforced or mass concrete foundations are used at almost all sites, but they require a large amount of material, involve high emissions (some toxic), are extremely heavy and cannot be recovered. It is surprising to observe that most recent constructions in which the environment is taken into account use such foundations. This paper presents the results of the research carried out on lightweight recoverable foundation solutions. The aim is to dramatically reduce the amount of material and allow the foundations to be deconstructed and recycled along with the rest of the building, leaving the land clear for reuse. Lightweight foundations, recoverable foundations, prefabricated foundations, site investigation. Lightweight recoverable foundations Lightweight recoverable foundations can be divided into two major groups: prefabricated and completed-in-situ foundations (cast-in-situ foundations are not considered because they pollute the subsoil and require large amounts of concrete). Timber piling (fig.1 to 3) is the lowest cost deep foundation material and lasts for over 100 years, with a natural taper that increases friction capacity. It can be easily delivered, handled and installed using existing driving equipment at close spacing, minimizing expensive floor slab thickness and resisting attack from acidic soils. It is also unaffected by stray electrical currents and no corrosion protection is required, taking advantage of a plentiful, natural renewable resource. Steel piles (fig.4 to 6) are either pipe piles or beam sections like an H-pile. driven into the soil by repeated impulsive loads. They may be cylindrical or expandable. Expandable mechanisms significantly improve the efficiency by rising the ratio bearing capacity / self weight. Opening extensions is accomplished during the final phase of the driving. LIGHTWEIGHT RECOVERABLE FOUNDATIONS ON SUITABLE GROUND Prefabricated foundations Cylindrical and under reamed piles of wood, steel or concrete Sheet piling – Strips and hollow or solid blocks Supports, tripod, bases, piers, plates Floating boxes or drums Helical and screw piles Grids Completed-insitu foundations Semi-precast foundations and formworks Micro piles Composite piles