Patent ID: 6881256
Filing Date: 2005-04-19
Classification: C04B,Y02W

Abstract:
1. A process for improving the fire resistance of an ultra-high performance concrete which comprises adding to the concrete organic fibers having a melting point of less than 300° C., an average length l of greater than 1 mm and a diameter Ø of at most 200 μm; the amount of organic fibers being such that their volume V ranges between 0.1 and 3% of the volume of the concrete after setting; the concrete having a characteristic 28- day compressive strength of at least 120 MPa, a flexural strength of at least 20 MPa, and a spread value in the unhardened state of at least 150 mm; the compressive strength, flexural strength and spread value being given for a concrete stored and maintained at 20° C.; said concrete comprising a hardened cementitious matrix in which metal fibers are dispersed and represent a volume V 1 of the concrete after setting, which is obtained by mixing, with water, a composition which comprises, apart from the metal fibers: (a) cement; (b) aggregate particles having a particle size D (c) pozzolanic-reaction particles having an elementary size ranging between 0.1 and 100 μm; (d) at least one dispersing agent; and satisfying the following conditions: (1) the percentage by weight of water with respect to the combined weight of the cement (a) and of the pozzolanic-reaction particles (c) lies within the 8-24% range; (2) the metal fibers have an average length l (3) a ratio, V (4) a ratio R of the average length l (5) the amount of metal fibers is such that their volume is less than 4% of the volume of the concrete after setting.