Abstract: A silt barrier comprises a plurality of filter elements, each filter element, in use, having a height direction, a width direction and a length direction and being adapted to allow the passage of water therethrough in the width direction and to resist the passage of silt therethrough in the width direction. In an embodiment the filter medium comprises a single type of material which combines: (a) filtration characteristics adequate to provide an effective silt barrier and; (b) deformation/resilience characteristics adequate to allow said filter element to return substantially to its original height after being compressed in its height direction by a vehicle passing thereover.

Abstract: A blockout device for at least partially blocking a through cavity of a concrete block and supporting a settable material comprises a frangible region adapted to accommodate conduits of various transverse sizes, by providing an opening the size of which can be adjusted to accommodate a conduit of any of a number of different transverse sizes.