What are Plastic Shrinkage Cracks?

These are cracks that start to form before the concrete has set (ie is still ‘plastic’), but which may not become evident until the next day. The cracks may form a random pattern or be roughly parallel to each other. They are typically 300 to 600 mm long and up to 3 mm wide (tapering very quickly over their depth). Although often quite small and shallow initially, subsequent movement can cause the cracks to increase in size and seriously impair the concrete’s performance.

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