Abstract: A light weight structural composite comprised of a cellular core having high dynamic load-bearing properties and a fiber reinforced resinous skin on all edges of the core and on the top and bottom surfaces thereof. The cellular core may comprise an array of balsa wood blocks, the skin may comprise a fiberglass reinforced epoxy or polyester resin, and the core and skin may be formed into a monolithic composite which is particularly suitable for use as a high strength to weight ratio ground opening cover.

Abstract: Wet soil containing up to about 40% by wet weight of water is stabilized into a relatively dry, compactable soil mass for use as backfill in excavations by admixing lime and an alkali metal salt of a starch-polyacrylonitrile or starch-polymethacrylonitrile graft copolymer with the soil, allowing the resulting admixture to stand for a short period of time to produce a relatively dry, compactable soil mass, and thereafter using the soil mass as backfill. The aforementioned graft copolymer can also be used as backfill around electrically conductive, grounding members by combining the graft copolymer with a binder or relatively water impervious material, such as a bentonite clay, and interposing the clay/graft coploymer mixture between the grounding member and the surrounding soil.