Abstract: A method of forming an underwater structure which includes fabricating an assembly consisting of an upper deck section, a lower gravity section and an impervious member secured in water-tight fashion to the lower peripheries of the deck and gravity sections. The assembly is floated with the membrane in a folded condition to the site and lowered so that the gravity section rests on the sea or river bed. The space between the sections and the membrane is filled with water and a non-settable particulate material to form a body of such material. The particulate body is drained to enable the external water pressure to exert a confining pressure on the body to render it coherent.

Abstract: A method of forming an underwater structure includes the steps of floating to the site an assembly consisting of a floatable structure and an impervious membrane attached to the structure, extending the membrane to cause a base portion to rest on the river or sea bed, filling the membrane with a body of particulate material such as sand, draining the particulate body to enable the external water pressure to render the body coherent, and supporting the floatable structure on the coherent body.

Abstract: A one piece building block suitable for load bearing applications such as road surfaces and river linings. The block includes an upper hexagonal portion and a lower portion having load bearing projections which, when the block is viewed in plan, project outwardly from alternate sides of the upper portion. Each projection extends substantially the entire length of its respective side. The lower portion has recesses of shape complementary with that of the projections to enable a plurality of identical blocks to be interlocked.