In the case of the subject floor there was also evidence of considerable curl at the intermediate saw-cut control joints. This was not a good sign. Curl is a result of significant loss of slab moisture and moisture loss is usually not that great between construction joints. Slab Shrinkage is Normal Shrinkage of the mass of a slab is always expected since all concrete mixes contain excess water for workability. This water should evaporate slowly over a period of one to two years.
Shrinkage occurs as moisture is lost.
My initial guess was that the mix either contained too much water or an additive was overused. It turned out both were good guesses. In other words, we want the entire floor to act in unison under traffic despite the fact we pour it in sections and further divide it by cutting or forming control joints. Ideally, as an MHV crosses a joint, the two slab segments should work together. If one segment deflects under load while the other stays high, edge damage occurs due to hard-wheel impact.