Abstract: Composition based on thermoplastic polymers, especially .alpha.-olefine polymers, such as polyethylene or ethylene copolymers, to which have been added, to promote degradation, a biologically degradable substance, an iron compound possibly complex and soluble in the composition, an oxidizable substance having one or several double bonds, selected from fatty acids and/or fatty acid esters, as well a further possible compound of a transition metal with the exception of iron as a catalyst. Said compositions demonstrate a markedly improved degradation capability when exposed to heat and/or ultraviolet light and/or sunlight and/or when in conditions promoting decomposition.

Abstract: Thin walled shaped bodies, specifically profiled building elements, which bodies are made of a hydraulically set material, comprise at the outer surface thereof a preferably strip shaped reinforcement at least at the area of the highest tensile load, e.g. at the wave trough of a corrugated board, which reinforcement is bodily and materially bonded to the shaped body. Such shaped bodies have a greatly improved strength for high loadings, such as e.g. in an application for building elements forming covering or roofing members.