A lime independent cementitious mixture including: an iron oxides constituent comprising one or more oxides of iron; and an activator. The activator is selected from one or more metal non-chloride salts, including metal phosphates and nitrates, or non-alkaline earth metal salts. The activator is also selected from those which may form one or more megalithic molecules with the iron oxides constituent when co-activated with water. A lime independent cementitious mixture including an iron oxides constituent comprising one or more oxides of iron; a silicates constituent comprising one or more calcined metal silicates; and an activator selected from one or more metal non-chloride salts which may form one or more megalithic molecules with the iron oxides and/or silicates constituents when co-activated with water.