A dry papercrete mix containing a pulp of fiber material such as newsprint and sharp sand, Portland cement and adding additional sand and/or pumice. The resulting dry, granular mix can then be handled stored and used in the manner which is conventional for concrete. The dry papercrete mix can be fortified with a fiber form of basalt which can be added to or substituted for all or a portion of the cellulose fiber content of the dry papercrete mix to provide a stronger structure when hydrated and cast into a desired shape with only a small increase in weight. Basalt reinforcing bars and meshes may be included in shapes cast from the hydrated mix in combination with or substitution for steel reinforcing structures. Including basalt in the mix and in reinforcing systems allows the design of joints between structural modules to provide exceptional strength in a unitary structure so formed.