| 摘要 |
The invention concerns the use of organic fibers having a melting point lower than 300 øC, an average length l more than 1 mm and a diameter not more than 200 micrometers, 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. The concrete has characteristic 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 said values being for a concrete preserved at 20 øC, said concrete consisting of a particularly hardened cement matrix wherein metal fibers are dispersed, which is obtained by mixing with water, which comprises apart from the fibers cement, aggregate particles having a particle size D90 not exceeding 10 mm, having elementary size ranging between 0.1 and 100 micro meters and at lest one dispersing agent. |
