ZEMENTZUSAMMENSETZUNGEN UND VERFAHREN ZU DEREN VERWENDUNG

A settable composition which can be applied by spraying to form a coating on a surface such as the walls of a mine comprises (i) a cementitious composition comprising the following components: (a) from 25 to 95% of calcium aluminate, (b) from 0 to 10% of lien and (c) from 0 to 50% of calcium sulphate, and where the sum of (b) and (c) is at least 5% the % being by weight based on the combined weight of (a), (b) and (c) and where the proportions of the components are such that the composition on hydration is capable of absorbing at least its own weight of water and (ii) an aqueous emulsion of an organic polymer, the amount of (ii) in relation to (i) being such as to provide a weight ratio of polymer, expressed as solids, to combined weight of (a), (b) and (c) of from 0.5:1 to 10:1, preferably 1:1 to 2.5:1 or (iii) a dispersible organic polymer and where the amount of dispersible polymer is such as to give a weight ratio of polymer to combined weight of (a), (b) and (c) o from 0.5:1 to 10:1, preferably 1:1 to 2.5:1. The dry composition parts (i) and (iii) above can be mixed with water in the mine.