Exactly right. Slump tests among others are required and have to be certified when doing DOT or state work. I'm sure California is more strict than any other state regarding this. Someone was paid off.
Next, the AG needs to investigate the inspectors office. At the very least someone was negligent, at the worse on the take. Neither should be tolerated and both should have ramifications, or else this kind of thing will happen again and again. Who inspects the inspectors?
I remember a story out of South Korea, something about a bridge being built with inferior concrete - beach sand (salt) etc. It was a disaster.
It's more than slump tests in Mo. If the concrete supplier has a contract to supply for a State or Fed job, the concrete batch plant has to be certified by a licensed indendent company and observed by the DOT district representative. They also test the materials (sand, rock, cement and admixes) that are part of the formula. If this were to happen in Mo, the only person to point at would be the plant operator who would obviously have cheated the mix after the state certification of the plant. Essentially dialing down the amount of cement in the mix as that is the most expensive component of concrete.
Could it be that this guy had his own "slump test inspector" on the payroll, and he was providing pre-cast concrete components -- with faked cement quality test data...?