The thing looks like it was made out of beach sand. All the places that failed, there arent many big jagged chunks, just very small aggregate and lots and lots of sand.
They were barely over half done. They still needed to build the section that was to go over the canal, OH, and dont forget that tall pointy thing that defies the constant gravity.
I wouldnt trust that concrete company to pour the foundation for my grand-kids playhouse!
Normally, as the concrete is poured, they take sample cylinders and run them over to the lab for testing. Who was in charge of that?