Abstract: A concrete includes organic fibers, dispersed in a cement matrix. The cement matrix includes elements having predetermined particle sizes. The organic fibers have predetermined lengths and diameters. The behavior of the concrete is improved both with respect to the occurrence of minute cracks and the propagation of large cracks as a result of a synergistic effect between the cement matrix and the organic fibers.

Abstract: The invention concerns the cementation of a well. A slag is used which comprises a hydraulic binder, a microsilica, a mineral addition, a superplasticizing agent and water, under defined granulometry and percentage conditions. The solublefigure relates to three compositions according to the invention but which differ by the origin of the microsilica. The invention applies notably to the cementation of an oil well.

Abstract: A process for spraying concrete or mortar, by a dry route or by a wet route, in order to produce on a surface a layer of concrete or of mortar. Just before or at the time of spraying, an aqueous suspension (A) of silica and of an aluminum compound chosen from aluminum sulphate, basic aluminum sulphates, alums and mixtures thereof is added to the concrete or mortar. The aqueous suspension (A) has a pH lower than 4, a solids content of between 10 and 50% by weight, and, after a period at rest of 48 hours, is in the form of a gel which is reversible under low shear. The aqueous suspension (A) is effective for increasing the thickness of the sprayed layer and reducing rebound of the concrete or mortar sprayed onto the surface.

Abstract: A method and composition for preparing concrete elements comprising the steps of mixing a composition comprising the following components expressed in parts by weight (p):a) 100 p of Portland cement;b) 30 p to 100 p or better 40 p to 70 p of fine sand having a grain size of at least 150 micrometers;c) 10 p to 40 p or better 20 p to 30 p of amorphous silicon having a grain size of less than 0.5 micrometers;d) 20 p to 60 p or better 30 p to 50 p of ground quartz having a grain size of less than 10 micrometers;e) 25 p to 100 p, or better 45 p to 80 p of steel wool;f) a dispersing agent;g) 13 p to 26 p or better 15 p to 22 p of water; and after setting, curing the concrete at a temperature of 250.degree. C. or higher, for a length of time sufficient to transform cement hydration products into crystalline hydrates of the xonotlite type; thus eliminating substantially all of the free water and at least the main part of the adsorbed and chemically bonded water.

Abstract: A metal fiber concrete composition for molding a concrete element, the composition being essentially constituted by a Portland cement, granular elements, fine elements for pozzolan reaction, metal fibers, a dispersing agent, optionally other additives, and water. The preponderant granular elements have a maximum grain size D of not more than 800 micrometers. The preponderant metal fibers have individual lengths 1 lying in the range 4 mm to 20 mm. The ratio R of the mean length L of the fibers divided by said maximum size D of the granular elements is not less than 10. The amount of preponderant metal fibers is such that the volume of preponderant metal fibers lies in the range 1.0% to 4% of the volume of the concrete after setting.

Abstract: A concrete structure including a rigid three-dimensional lattice of concrete bars which are interconnected at nodes. The lattice is constituted by an assembly of prefabricated cast blocks, in which each block comprises a node and a plurality of arms (14) radiating from the node. Each arm has at least one longitudinal socket with an opening in the free end of the arm, and the arms of two blocks are assembled in aligned end-to end pairs to constitute the bars of the lattice. The sockets of assembled arms are in alignment and contain a common metal reinforcing member, and the junction zone of the arms is surrounded by a clamping sleeve, with the sockets being filled with hardened mortar. The lattice is prestressed by prestress cavles passing outside the bars of the lattice and fixed to some nodes of the lattice.

Abstract: Concrete; structural elements having a high permissible working load typically in the range of at least 50-100 MPa. The element includes a block of compressed concrete surrounded by a tubular hoop made of intercrossed wires. Such elements are useful for making beams, posts, cables and the like.

Abstract: A ballastable concrete base for an offshore platform is essentially constituted by a volume formed by a three-dimensional lattice of concrete bars interconnected at concrete nodes. Some of the nodes are interconnected by prestress cables passing outside the bars and optionally past intermediate nodes. The cables three-dimensionally prestress the lattice as a whole, and the base further includes means for making watertight the side and the bottom of the lattice.

Abstract: A concrete structure including a rigid three-dimensional lattice of concrete bars which are interconnected at nodes. The lattice is constituted by an assembly of prefabricated cast blocks, in which each block comprises a node and a plurality of arms (14) radiating from the node. Each arm has at least one longitudinal socket with an opening in the free end of the arm, and the arms of two blocks are assembled in aligned end-to-end pairs to constitute the bars of the lattice. The sockets of assembled arms are in alignment and contain a common metal reinforcing member, and the junction zone of the arms is surrounded by a clamping sleeve, with said sockets being filled with hardened mortar. The said lattice is prestressed by prestress cables passing outside the bars of the lattice and fixed to some nodes of the lattice.

Abstract: A prefabricated three-dimensional truss structure for a bridge, or the like, the truss formed from bars arranged to define triangular or rectangular patterns. The bars are formed from prestressed, high-strength concrete that are connected at their ends with assembly blocks that are prestressed, the prestress being preferably provided by the cables that prestress the bars, and which terminate at the blocks. A plurality of such unit trusses can be assembled to provide a truss structure for a bridge span, and the trusses can assume a wide variety of configurations.

Abstract: A bridge has prefabricated sections and is prestressed externally of the concrete of the sections by cables. Each section has upper and lower decks, interbraced by longitudinal oblique webs which form dihedrons. Certain dihedrons are closed by transverse panels. The panels assure the desired deviations of the prestressing cables as well as their anchoring.

Abstract: This invention relates to a prestressed concrete structure which behaves like a hollowed out slab.The structure combines a lattice work structure and a prestress by external cable, maximally optimizing the advantages of these two techniques. The Figure represents a part of the floor of a bridge according to the present invention. The floor comprises two tables 6 and 7 which are joined by a lattice work composed of pyramids P. Prestressing cables 8, 8' and 9' pass between the tables outside the concrete of the bars of the pyramids.The present invention is used for the construction of bridges, roofings and floors.

Abstract: This invention relates to a production of a structure by means of arch stones. The arch stones comprise series of mixed steel-concrete arch stones (V.sub.M), each comprising a metal frame of steel integral with an upper concrete slab, these series being separated by interposed concrete arch stones or sections, (V.sub.B), the assembly of the arch stones being reinforced longitudinally by prestress cables which penetrate the metal frames and are attached at their ends to the concrete arch stones. This invention may be applied to bridge floors and similar structures.

Abstract: The invention relates to an apparatus and method for manufacturing concrete structural elements. In order to manufacture the elements, setting of the concrete takes place in a casing (1), while the concrete is compressed with an axial pressure of at least 50 MPa and the casing is surrounded with a hoop (2,3) so as to create transverse planes of pressure.

Abstract: This disclosure relates to the extension of a portion of a deck using deck segments, by means of a cable stayed beam resting on a front hinged support and on a rear support.In a first phase, the overhanging segments are suspended from the beam in a manner known per se and the part 5a of the beam which is downstream of the front support 6 is maintained substantially steady. In a second phase, the segments are joined to said portion by producing a prestress accompanied by a progressive swinging movement by said rear part of the beam.This invention is used for the construction of the deck of a bridge.

Abstract: The invention relates to a continuous boring or cutting machine provided with tools animated by a sweeping movement, said machine comprising a plurality of tool-holders mounted to oscillate on a rotating structure, these oscillations being controlled in synchronism by a rotary jack coaxial with respect to the rotating structure, the rod of the jack being fast with an element to which each tool-holder is connected by a connecting rod having a foot jointed on to said element and having a head jointed on to the tool-holder. The invention is more particularly applied to tunneling machines.

Abstract: The invention relates to a tunneling machine or other machine provided with tools for cutting materials from a wall located in front of the machine, said machine comprising a movable frame carrying a head rotatably driven about an axis, said head bearing at least one bucket for picking up said materials after cutting and for dumping the materials on or towards a conveyor, said bucket having an inlet opening for picking up the materials when the bucket passes through a low position during the rotation of the head, and said bucket having an outlet opening for dumping the materials, said outlet opening being offset to the rear of the head with respect to the said inlet opening.