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.

Abstract: An extensible beam (1) comprising: a first, elongate element (10), a second element (50) adapted to move relative to the first elongate element in order to vary the amount of overlap between the first and second elements and thereby vary the length of the beam. Wherein the first element includes first (18) and second (20) support portions and the second element includes first (52) and second (54) spaced apart strut members for engagement with the first and second support portions respectively.

Abstract: An extensible beam (1) comprising: a first, elongate element (10), a second element (50) adapted to move relative to the first elongate element in order to vary the amount of overlap between the first and second elements and thereby vary the length of the beam. Wherein the first element includes first (18) and second (20) support portions and the second element includes first (52) and second (54) spaced apart strut members for engagement with the first and second support portions respectively.