Abstract: A concrete reinforcing metal fiber capable of being easily and uniformly dispersed in concrete. The metal fiber integrally includes a longitudinal strength body which bears tensile force that works thereon, and two rows of intermittent fins extending on the opposite sides of the strength body. The flatness ratio, namely, the ratio of the maximum width of the metal fiber to the maximum thickness of the same, of the metal fiber is in the range of 2.5 to 6.

Abstract: The inventive prosthetic body for bone substitute is a sintered body of hydroxyapatite and characterized by the open pore structure with a pore diameter in a specified range forming a porosity of 20 to 40% and a bending strength of at least 100 kg/cm.sup.2. The sintered body can be prepared by blending powders of hydroxyapatite and a thermally decomposable substance, e.g. crystalline cellulose, each having a specified particle size distribution, in a specified proportion and shaping and sintering the powder blend.

Abstract: A concrete reinforcing steel fiber has an alternate arrangement of basic portions corresponding to the body of the steel fiber material, and section-shaped portions formed by pressing the steel fiber material between a grooved forming roller and a toothed forming roller. Each section-shaped portion has a flat upper surface, lateral projections and a round bottom. The pressure bearing area b of the section-shaped portion, namely, the sum of the cross-sectional area of the lateral projections and the area of the end surface of the basic portion contiguous with the section-shaped portion, is in the range of 0.2A to 0.5A (A=cross-sectional area of the basic portion). The total pressure bearing area B of the steel fiber is in the range of 3A and 8A, and also in the range of 0.02T and 0.08T (T=tensile strength of the steel fiber).

Abstract: The sintered microporous hydroxyapatite material of the invention is useful as an artificial bone substitute material either in a granular and slurried from in a physiological saline solution used as a filling material for lost portions or cavities of bones or in a form of a shaped prosthetic bone substitute member. The inventive material is characteristic in the open pore structure of micropores with a pore diameter distribution in the range from 0.01 to 0.10 mm and a porosity in the range from 20 to 50%. When the material is used in the form of a granular bone filling, the particle diameter thereof should be in the range from 0.1 to 2.0 mm. When the material is used as the prosthetic bone substitute member, the shaped body should be formed of the matrix of the inventive microporous material and pores with a pore diameter distribution in the range from 0.2 to 2.0 mm.