| 摘要 |
2102309 9219431 PCTABS00017 In accordance with the invention, a concrete conduit (2) is completely encased within a shell (3) of a plastic resin such as polyethylene. The plastic shell (3) functions to insulate the concrete conduit (2) from mechanical shocks thereby preventing breakage and cracking of the conduit (2). The shell (3) also effectively provides an impermeable barrier for water vapor and a smooth, relatively frictionless, surface for receiving electric cables, wires and the like. The conduit (2) is made by preforming the shell (3), for example by rotational molding, and filling the shell (3) with pourable cement (2) through a filler hole (9) in the shell (3). The filler hole (9) can then be closed with a plug of the resin used to form the shell (3). |
