this invention refers to the manufacturing of structural and impervious members by slurry - infiltration in a 3 - dimensional mat system , which consists of single layers . the single layers are preferably meshes . the structural system is a composite material consisting of a 3 - dimensional micro reinforcing and sieving mat system bonded in concrete . the aggregate can be precisely positioned horizontally and vertically in the member by variation of the mesh width of the single layers . the sieving effect by the variation of the mesh width in vertical direction guarantees a positioning of aggregate by size . by this effect the load capacity , the stiffness and the crack propagation can be controlled and adjusted precisely .