My friend in Colorado is an engineer who was in charge of building roads and bridges in Boulder county, CO.
I asked him why they would demolish the concrete pilings. He said it was probably because they did not properly sample the concrete as it was being poured for proper air content. The result would be substandard concrete that would have to be taken down and done again. Without being there , that was his best guess.
Air entrainment, as it is called, is only one component of concrete workability and longevity but primarily in areas subject to freezing and thawing.
I doubt that is the reason.
They may have been poured in the wrong location or they were not deep enough or they poured the concrete with too much water (very common in DR) or they left out a specified admixture, says for chloride resistance to slow steel corrosion. Or even perhaps the reinforcement was not what was specified in the design.
In any event an engineer should be inspecting the work, verifying it and checking concrete mix tags to verify it meets specified design mix.
And then follow up with test cylinder breaks to confirm minimum design strength is met at the specified time.
I have done many bridges and there are a myriad of factors. You have to be careful that onsite water it not added to make concrete more pumpable or workable for the finishers.
I had a Turkish foreman add double water on dry mix trucks used in the Saudi heat, all because the Filipino driver could not or was afraid to tell him he already added the correct amount.
I noticed something was wrong when they stripped the column forms after 3 days and it had a strange sheen none of the other columns had and I could stick my pocket knife into the column.
Needless to say it was jackhammered down in the next few days after I investigated what happened.