Formwork comprising a plurality of interconnectable formwork elements

Formwork, comprising:

• a plurality of interconnectable lightweight formwork elements, each of said formwork elements being an elongated, substantially cylinder-shaped member having an interior, each of said formwork elements having thin side walls which are resilient so as to enable stacking of one element within another element for transport and being sufficiently strong to be self-supporting when each formwork element is positioned with a longitudinal extent thereof in a vertical direction, said interior of each formwork element defining a longitudinal chamber,
• each formwork element including means along said longitudinal extent for interconnection of said formwork elements, said means for interconnection extending along longitudinal edges of said side walls of said formwork elements,
• each of said formwork elements having means for defining at least one aperture in an element portion mutually displaced from a longitudinally through-going aperture defined by said means for interconnection extending along said longitudinal edges, so that each of said formwork elements is of a substantially C-shaped cross-sectional form, and
• said means for interconnection on each formwork element being releasably engageable with the means for interconnection on each other formwork element, and being located on said formwork element such that when said means for interconnection are interconnected said formwork elements are located so as to close said apertures externally of said side walls of said formwork elements while also connecting said apertures internally of said side walls of said formwork elements in order to prevent leakage out of the interconnected formwork elements while establishing fluid communication between adjacent chambers defined by said interiors of said interconnected formwork elements.