It has been found that the inclusion of certain additives in a composition which comprises a mixture of sulphur and mineral filler, e.g. sulphur-based concretes, mortars and surfacings, yields as a result compositions which have improved ductility when compared with such compositions without the said additives, because it makes a hot- mouldable sulphur composition which is otherwise sensitive to water, e.g. a concrete, mortar or surfacing comprising sulphur and a mineral filler, resistant to water. It has also been found that the inclusion of certain additives in a composition comprising a mixture of sulphur and mineral filler, e.g. a sulphur-based concrete, mortar or surfacing composition in which the mineral filler is contaminated with an expanding clay, yields as a result compositions which have good water resistance and which do not disintegrate at all when they are submerged in water for prolonged periods. Without these additives use of a mineral filler contaminated with expanding clay normally results in failure of the sulphur compositions when they are exposed to wet environments. Many additives which have been found to be effective for improving ductility also improve water resistance when an expanding clay is present in the mineral filler. Because of this a concrete, mortar or surfacing with improved ductility and resistance to water can be produced from a mineral filler contaminated with expanding clay. The additives which can be used to increase water resistance include crude oil, resin and the petroleum (malthene) fraction of crude oil, the residual fraction (malthene and asphaltene fractions) of crude oil, the heavy fractions of crude oil, in particular those distilling above 250 degree C, polyols, e.g. glycerine, and Varsol (a registered trade mark of the Humble Oil and Refining Co. for an aliphatic petroleum solvent) and other similar products. In one aspect of the invention a ductile hot-mouldable composition for construction, e.g. a concrete, mortar or surfacing, containing sulphur and a mineral filler is provided. In another aspect the invention provides a water- resistant hot-mouldable sulphur composition, e.g. a concrete, mortar or surfacing, which contains a mineral filler contaminated with an expanding clay. In yet another aspect the invention provides a water- resistant ductile hot-mouldable sulphur composition, e.g. a concrete, mortar or surfacing, which contains a mineral filler contaminated with expanding clay. In another aspect the invention provides sulphur concrete articles formed from hot-mouldable concretes. In another aspect the invention provides a sulphur mortar of improved ductility which can be melted. In yet another aspect the invention provides a water- resistant sulphur mortar which can be melted, of improved ductility, in which the mineral filler is contaminated with an expanding clay. In another additional aspect of the invention processes are provided for the preparation of ductile moulded sulphur concrete articles. However, in another aspect, the invention provides processes for the preparation of water-resistant moulded sulphur concrete articles which contain a mineral filler contaminated with an expanding clay. In addition to this the invention provides processes for the preparation of water-resistant ductile moulded sulphur concrete articles which contain a mineral filler contaminated with an expanding clay. In a special embodiment of the process according to the invention the mineral filler is first soaked with a polyol. In a different aspect the invention provides a method for making a sulphur concrete which contains an expanding clay resistant to water. In the case of the additives which improve ductility, this ductility is improved for both mineral fillers which are free from expanding clay and mineral fillers which are contaminated with expanding clay. The terms "hot-mouldable" and "moulded" in this description cover sulphur compositions, e.g. concretes, mortars and surfacings, which can be first poured into moulds or forms, or poured, extruded, applied with a trowel, applied by spraying or applied by other means to the site for which they are intended for installation in situ when the sulphur is in a molten state below 160 degree C, as is the case with Portland cement concretes. In combination with the additives according to this invention other conventional sulphur modifiers used for the manufacture of sulphur compound materials, e.g. sulphur concretes, may be used. It may be convenient to incorporate such modifiers, including plasticisers and combustion retardants to provide special properties for specific applications and end uses. For example, when plasticising is required, additives such as olefin hydrocarbon polymers can be used (United States Patent 4,058,500 - Vroom, the description of which is included here for reference) and dicyclopentadiene. Likewise, when for example compositions of improved resistance to combustion with a flame are required, combustion retardants such as 1,5,9-cyclododecatriene can be added.