Abstract: Method of producing concrete structures with a surface protection layer and a concrete layer. The method includes moulding the concrete layer and the surface protection layer using a "wet in wet" process. The surface protection layer preferably consists of a cement allied mortar having a low water binding average ratio and a binding agent strength above 70 Mpa. The concrete layer which preferably consists of a concrete having a lower binding agent strength than the surface protection layer, is preferably an air entrained ballast concrete with dense structure and a strength in the range of 10-20 Mpa. The surface protection layer is cast in the bottom of a mold, and the concrete layer is cast above the surface protection layer. During desiccation of the material, the surface protection layer shrinks less than the concrete layer, so that pressure strains are created through deformation differences in the surface protection layer and concrete layer.

Abstract: Method of producing monolithic mainly cementbound concrete in the density range of 650-1300 kg/m.sup.3, preferably of 800-1200 kg m.sup.3 with substantially good placing properties both for building in situ and prefabrication. The concrete consists of cement mortar with an air-void volume of 7-18% of the total concrete volume and aggregate consisting of lightweight organic or inorganic material. The smaller particles of the aggregate should be spherical, exceptionally lightweight, hydrophobic and durable against deformation in order to reduce the water content without changing the consistency of the concrete.

Abstract: The present invention relates to a method of producing a cement mortar with a density of 1200-2000 kg/m.sup.3 with good stability in a fresh condition. According to the invention, this good stability in the mortar is achieved through an extremely fine-pored structure initiated by fine-particle material with certain fixed properties added to the fresh mortar. The invention also comprises a method, using said mortar as a binding agent, of producing a lightweight aggregate concrete with an aggregate content of 45-80 percent by volume and a density below 1400 kg/m.sup.3 where the aggregate material has a particle density of less than 1200 kg/m.sup.3 and the mortar entirely fills out the space between the aggregate particles.