| 摘要 |
1384117 Moulding concrete pipes HUMES Ltd 21 Feb 1972 [26 Feb 1971] 7989/72 Heading B5A [Also in Division F2] A concrete pipe (or other hollow body) lined with sheet material is formed by casting concrete between a vertically disposed mould 6 and core 7 that supports a ribbed sheet 1. After settling for a period of time, the concrete is vibrated 10. The plastics sheet 1 is arranged with the ribs running transversley or longitudinally of the core 7, which may be only partially enveloped. The ribs are diamond shaped (Fig. 3) or triangular (Fig. 1, not reproduced) in cross-section. The concrete is vibrated during casting, allowed to settle for 30 minutes, and then vibrated for 1 minute. The mould and core are removed before or after the concrete is fully set. |
