University of California, Berkeley, civil engineering professor Robert Bea said cracking in high-strength reinforced concrete structures is never expected.
My entire life concrete specialists and sensible engineers have always said, "Reinforced Concrete cracks." It is always a question of how much, where limited, how controlled etc. Reinforced Concrete is not an homogenous material entirely uniform throughout.
I don't like the part where they are saying that they already are concerned about a funky Mix Design on the concrete. That shows me that there were questions and issues about this during design and mix approval. I never, never want to place a significant concrete placement where there is no "history" of performance of a specific mix design from the nearby plants with the selected aggregate source and mix. I had a competitor once who beat me out of a big runway job and that idiot used an aggregate sizing that had never been used from that quarry before in his runway mix. The runway failed and was out of service for over a year with millions in repairs.
Now all that being said, I would like to walk the spillway and look at it myself. Cracks are due to many issues. Shrink cracks, "D" Cracks, Plastic Cracks, "Y" Cracks, Sub-Grade swell or subsidence cracks, stress cracks, and on and on.
Most people do not understand that hairline cracks where you still have aggregate interlock are not a really significant issue in many types of horizontal surfaces. This pig is not very forgiving as we have previously found out.
I must maintain confidentiality on this matter.