Is there always a ground wire I have a hot and a neutral then there is a 3 conductor wire wired together inside the junction box. Can I use this as a ground?

Ground wire is either green or bare. When coming from a cable it is bare.

If the wires that are wire nutted together is white, it is probably part of your switch wiring.

It can not be used as a ground.

If u can post a picture, we sill be able to tell u for sure if it is a ground or part of a switch leg.

Chuck

The wire colour is blue and there are 3 wires nutted together in a group

Let me rephrase this there are 2 wires wire together with each wire is a group of three wires they are all blue in colour.

Let me rephrase this there are 2 wires nutted together, each of the (2) wires in this connection is a group of three wires, they are both blue in colour. No pic available. There is also a red single wire (hot) and a white (neutral). The white wire is also a group of three wires ganged together(neutral. Is it possible that there is no ground wire provided it is a cast in place concrete junction.

Metal raceway, such as conduit, BX cable, etc, can act as the equipment ground. If the box is embedded in concrete, I suspect there is metal conduit, and is allowed to be the equipment ground. You can use a volt meter, test across the live wire and the metal box, if you read 120 volts, then I would be confident the conduit is the ground.

You either need to start over with exact details or provide a pic of the box.
Personally I have NO idea what you are trying to describe.

azuccolo, why did you start a new thread? This is part of another one where you talked back and forth many times so you know how to reply to a post. No need to start a new one , it confuses folks.