| 摘要 |
Each block of a sleeper is moulded in a mould comprising a bottom 1, two longitudinal walls, two transverse walls 4, 5 in which are made orifices 25, 28 for passing retractable lugs supporting at least one reinforcing grid. The passage orifices 25, 28 have a cross-section of annular shape which is identical to that of the retractable lugs. The grid-support lugs are introduced, the grid is introduced into the mould through its free edge 6 and it is placed on the support lugs, the material is poured into the mould, the support lugs are withdrawn, the block is released from the mould and it is hardened (cured, set). By placing the grid on the support lugs 31, 32, it is fixed in position with respect to the free edge 6 and to the longitudinal walls of the mould and the transverse walls 4, 5. <IMAGE>
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