| 摘要 |
The disclosure embraces a method of securing a protective thermoplastic sheet to a surface of a building block which is provided with a locking groove on its side surfaces, the method including the steps of placing the block in a receptacle and passing the block and receptacle beneath a device for supplying a heated thermoplastic sheet which covers the surface of the block and the opening of the receptacle, drawing a vacuum in the receptacle to pull the sheet material securely into the groove formed in the block so that when the sheet material cools, it will be securely anchored in the locking groove provided on the block.
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