concrete casting

Hello, I wondered if anyone knows where I can easily get hold of some kind of concrete plasticizer, or anything that will improve flow at low water quantities? Mortor plasticizers are readily available but I read that they shouldn't be used with concrete as their air entraining qualities weaken...

I'm building a pair of pillars which will be filled with concrete for strength. I'm going to need to place bolts at the top of each to attach a steel joist that will span the gap between them. I'd like to use the kind of bolt that you put in place before you pour your concrete, as I understand...