A:
I'm not a concrete expert, however my understanding is that during the cure process, water is hydrated into the mix generating heat. While that process is continuing over the days or weeks following a pour, warmer temperatures would show where the curing is less complete.
Following the time for a "complete" cure, water intrusion deep into a concrete mass should be the same temperature as its' surroundings, since no more curing is taking place, and evaporation is blocked by the mass of concrete surrounding the water. Intruded water near the surface should evaporate cooling the surrounding concrete - the Fluke 62 can detect this cooling.
You should also consider the Extech photo IR thermometer, our 39753-08, which takes a picture of the point at which the thermometer is directed, as shown by the aiming laser. This lets you see the cooled area and even take still photos or video; it is about 1/2 the cost of an IR camera.
Answered on 2/6/2013 by Jon from Technical Support