spotting, molting of 6000 psi conc slab

[BGRIDDLE]

A plant manager wanted 6000 psi concrete with #8 bars each way, #4 bars each way, and a layer of WWR in a 10" slab. I bid the job and was hired. The fact that the guy was changing things along the way (including the size of a machine pit for which I had already sent drawing to a steel fab.) He had production on the machine which resided on the slab stopped while the old slab was demo'ed. and the new slab w/ 25 3'dia. x 4' deep mini pilings dug. He wanted the work done in 1 week and he was 2 days late getting off the slab. ANyway....we met his schedule (despite him NEEDING the soil under the slab sprayed for termites, AND forgetting to tell us the company he worked for had a contract with a different termite treatment company,which we had no way of knowing, and while he watched the company I contracted DO the spraying). Now that the conrete is down- it appears as though the Conspec cure and seal WB that we used left a slightly spotty effect on the surface. The 40' x 40' slab was floated and hand troweled so burnishing is not the cause. It is obviously only an aesthetic quality, but the guy is witholding 10% of a 35,000 job. Any ideas what caused this effect?

 

[frv]

This could be way off..

In my company we frequently restrict the use of fly ash in visible concrete, as we have had problems in the past with uneven color. It's hard to know if what you're describing is like what we've experienced before, but that could be one culprit.

 

[BGRIDDLE]

As the spotting begins about 6" inside the edge of concrete, it appears consistent with where one would be standing at the edge of existing concrete to spray the curing, hardening, dustproofing compound. I am not aware of how that would interact with fly ash content, but I'm guessing it's possible. I know fly ash is not recommended for concrete to recieve color, but I guess that's one for the chemists to answer. In any case- I appreciate the response.