Upper left of post 28. Looking closer, it seems to be stucco mesh. Seeing this makes it no wonder the Olympics venues of 2008 are already falling apart.
I looked at that 6-8” square piece, a poor picture, BUT it sure would lead one to think of stucco mesh. Earlier posts spoke of the poor quality of concrete. The pic at #28 sure shows no large aggregate all sand to 3/4”- size -— Nice.