Abstract: A concrete in which metallic fibers are dispersed, obtained through mixing with water a composition including a cement; ultrafine elements with a pozzolanic reaction; granular elements distributed into two granular classes (C1)>1 mm and <5 mm and (C2) ranges from 5 to 15 mm; cement additions; an amount of water E added in the mixture; a dispersant, and preferably a superplasticizer; metallic fibers, in an amount maximum equal to 120 kg per m3 of concrete, the contents of the various components (a), (b), (C1), (C2), (d) and the amount of water E, expressed in volume, meeting the following relationships: ratio 1: 0.50?(C2)/(C1)?1.20; ratio 2: 0.25?[(a)+(b)+(d)]/[(C1)+(C2)]?0.60; ratio 3: 0.10?(b)/(a)?0.30; ratio 4: 0.05?E/[(a)+(b)+(d)]?0.75; ratio 5: (d)/(a)?0.20. The invention applies to the manufacture of voussoirs without frameworks, of tiles and of elements of the plate, shell type or the like.

Abstract: The invention concerns the use of organic fibers having a melting point lower than 300° C., an average length l more than 1 mm and a diameter Ø not more than 200 ?m, in ultra high performance concrete for improving the concrete fire resistance, the amount of organic fibers being such that their volume ranges between 0.1 and 3% of the concrete volume after setting and the concrete having a compressive strength at 28 days of at least 120 Mpa, a bending strength of at least 20 Mpa, and a spread value in non-hardened state of at least 150 mm, the values being for a concrete preserved at 20° C., the concrete consisting of a particularly hardened cement matrix wherein metal fibres are dispersed.

Abstract: A concrete in which metallic fibres are dispersed, obtained through mixing with water a composition comprising:

Abstract: The invention concerns the use of organic fibres having a melting point lower than 300° C., an average length l more than 1 mm and a diameter Ø not more than 200 &mgr;m, in ultra high performance concrete for improving the concrete fire resistance, the amount of organic fibres being such that their volume ranges between 0.1 and 3% of the concrete volume after setting and the concrete having a compressive strength at 28 days of at least 120 Mpa, a bending strength of at least 20 Mpa, and a spread value in non-hardened state of at least 150 mm, the values being for a concrete preserved at 20° C., the concrete consisting of a particularly hardened cement matrix wherein metal fibres are dispersed.