A modular slab, slab system, piles and methods of use thereof are described along with specific applications and methods of manufacture. The slab or slab system may be pre-insulated and pre-finished before being assembled on site. The slab system may be advantageous to use as a replacement for traditional in-situ poured building foundations. The slab system may also have uses in other fields such as for floors, roads, bridges, pavements/side walks and other civil and structural applications.