obscure cast concrete question

Can someone please tell me what the small cylindrical indents are in cast concrete panels as per the attached image.
And what is the purpose of them?
I thought at first they supported the reo bar, but when you look at them up close you cant see any steel - just a clean cement finish.

I believe they are an affect of the cast in place molds. Maybe the left over impresstion from bolts?

sometimes they use internal re-bar that’s stretched out while the concrete sets, then is cut off… making a tensile kind of concrete that’s stronger. Those could be artifacts from that process, though if you say you can’t see metal, maybe that isn’t it

They’re not post-tensioned cables, for sure. Those would not be found on the “face” of the panels, only side to side, or top to bottom. There is no real reason to have those indentations, other than purely aesthetic. You can cast concrete in forms very smoothly (as it looks like they tried to) and these indentations were probably intentional. If it were remnants of bolts, etc. the void left would be very jagged and uneven.

The indentations are left after the form ties are removed – concrete forms are held together by ties at regular intervals to counter the pressure of the concrete on the forms. Sometimes they are filled sometimes not.

They are called “form tie holes.” They are created by the metal ties that hold the two sides of the form-work together. You’ll notice they are using 4’x8’ sheets of wood to create the forms and then you have the holes spaced properly to hold everything together. A lot of times they will come back and patch the hole or put a metal plug in as a decorative finish.

Thanks for the replies. The form tie holes makes sense. I really like the look - I have just always been interested if it was a purely aesthetic choice or if it did serve a purpose.

Looks like I need to further educate my guesses…

I’m sure you have seen Tadao Ando’s work with this. His stuff is amazing!