Second this value from former civil/structural engineer. That’s what we used in every single concrete design class I took.
And before you ask that’s a good value for both unreinforced and reinforced concrete 
165lbs approx.
7.4805 gallons per cubic foot
8.33 pound per gallon
thus a cubic foot of water weighs 62.31 lbs
aggregate producers typically mine and crush limestone for use in concrete
and asphaltic concrete. Specific gravity of the raw mineral (sand and gravel)
is typically 2.65, give or take. Cement is a little lighter but there isn’t much compared to aggregate content.
7.4805x8.33x2.65 is as close as you’ll get without factoring in dry cement SG
that of course does not take into consideration the weight of rebar if used
Don’t forget the embedded air, and also that most (I think) of the water will evaporate from the concrete after catalyzing the cement powder
Not really. The water doesn’t “catalyze” the cement powder; through hydration, water forms chemical bonds with the cement. (here’s a little CE101 page if you’re interested, this page also has the concrete professors’ favorite refrain: Under no circumstances should the word “cement” be used to refer to the composite product “concrete”. ) So there isn’t a lot of water to evaporate as it’s used during hydration.
Wet concrete is essentially the same volume as cured concrete with shrinkage of usually much less than 1%. Which is one reason why it’s such a great building material. So using the standard weight of 150 pounds/cf (which is the weight most engineers use for their calcs, it’s the highest and, therefore, most conservative) for both weight and cured concrete is fine.
And enineers usually don’t bother to calculate the weight of the rebar. It’s true steel is 490 lbs/cf compared to concrete’s 150 lbs/cf but you usually use such small amounts of rebar that it’s not worth the time to calculate.
You’re right, didn’t consider entrained air! That accounts for the 150 rule of thumb most engineers use I presume.
Interesting. So you are referring to the barest, minimum amount of water required to hydrate (not catalyze LSNT) My use of “evaporation” which isn’t quite the right term either for what I meant comes from my experience in concrete construction. After pouring a floor or beam there would be water that would rise to the surface. Admittedly this water would be there because we were using more than the minimum amount of water. (It didn’t really matter since the concrete would still cure to a strength well beyond the engineer’s specs.)
Yeah, you have to add a littlemore water than absolutely necessary for workability (particularly with things like beams where you need to make sure the concrete works down around the rebar cage). And it’s true we usually use a pretty conservative concrete strength for our calcs. But you really don’t want to use a whole lot of excess water 'cause it’ll actually decrease the concrete strength. Usually the concrete guys carefully calculate the water to cement ratio (and check it with a slump test which is excatly like it sounds) so you get sufficient workability with the required strength. Here’s a good paragraph from that page I linked above:
Mant thanks for all the responses. Never thought I’d get so many responses regarding concrete.
Imagine if I’d inquired about silicon…