ABSTRACT
Both L-shaped concrete specimens showed hairline cracks at the tip of the the boundary between the deep and swallow sections of the mould. One of the specimens also showed a clear crack just below the surface of the concrete.This crack was not visible at the surface of the concrete, but only from the side. Figure 1 shows images of this specimen. The photo in Figure 1a was taken through the transparent side panel just after its first appearance at 80 minutes. The photo in Figure 1b was taken after 360 minutes with the transparent side panel removed.
