correct mixture for concete

Add enough water for consistency. Just remember, it is easy to over water. Put in a little and mix the RUE. Then after thorough mixing, add a tad more (at a time) till you get what you want.

On fence posts we never add water. We mix it all good (dry), put in the post, put in the dry mix; tapping good as we go and let nature set the post. This way we can do the fence all at once rather than having to set the posts and come back in a few days and finish the fence. The dry mix holds nicely while had we watered it, the post would have flopped around. After 6 mo or so the concrete will solidify.

FYI: I have removed fencing years later that I built like this and I guarantee you that I couldn't tell by looking at the concrete that I had put it in the hole dry..... had a good bear hug on the post.

Mark

1:2:3 by volume - cement:sand:stone is a very common, strong mix. 3/4" crushed stone is used for most projects, except thin or small ones where 3/8" would be more appropriate. For an 18" post, 3/4" stone should do just fine.

Rod

I'd think a mixture of 5 to 1 would be about right, as Rod suggests.