BUILDING BLOCKS
1348253 Moulding dove-tailed blocks T F NEWELL 18 Nov 1971 [5 Nov 1970 21 April 1971] 52742/70 and 10572/71 Heading B5A [Also in Divisions E1-E2] Dry walls are built up by arranging blocks 10 (Fig. 1) with undercut lower limbs 13 of two adjacent upper blocks in upper undercut groove 11 of a lower block, the grooves tapering across the block. Cavities 14-16, which may be round, receive reinforcing rods or concrete filling. A foundation block allowing an inclined wall and a coping block are included. The blocks may be ceramic, concrete, plastics or metal, with a facing. Apparatus for moulding the block comprises a vertically movable mould 25 (Fig. 9), the internal walls of which correspond to the shape of the block, a base member 28 for supporting a moulded block and removable cores 26 for forming cavities in the block. Pressing is applied, and the article surface brushed 27; the block is steam or gas hardened.