A refractory article used at high temperature contains a silica, calcium silicate or mullite matrix with at least a surface having an open porosity filled at least partially with a sulfate, phosphate, or carbonate salt or a mixture of sulfate, phosphate or carbonate salts. The refractory article is resistant to the corrosion and build-up of non-ferrous metals and their alloys.

A concrete having a smooth surface, which is wholly or partly coated with a polymer film obtained by polymerisation under the action of radiation, where the film is itself wholly or partly coated with a thin photovoltaic film.

A concrete having a smooth surface, which is wholly or partly coated with a polymer film obtained by polymerisation under the action of radiation, where the film is itself wholly or partly coated with a thin photovoltaic film.