0433 HOLLOW & SOLID CONCRETE BLOCKS
04331 Manufacture and Curing
Concrete blocks shall be obtained from an approved supplier or may be manufactured on site. Samples and test results shall be submitted for approval by the Engineer before any blocks are delivered or used in the construction of the works.
Blocks shall be manufactured from cement and aggregates complying with the requirements of ES CD3 201, and/or pumice with no fine volcanic dust.
The Contractor shall prepare design trial mix using the available materials to give the average minimum compressive strength as specified in the compressive strength requirements of this section after casting and curing of 28 days. A minimum of 9 blocks shall be prepared from this mix for testing.
Blocks shall be uniform in texture, shape, size, with sharp arises and free from any cracks or defects.
Blocks shall be produced under shed on a suitable smooth floor.
Only machines of approved design shall be used for the manufacture of blocks.
Blocks shall remain under shed and wet cured for a minimum of 7 days after casting.
The surface characteristics of blocks shall be such that a good key for plaster or render is provided where required. Blocks shall not leave their place of manufacture before the age of 28 days.
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