[Shotimes] Semi OT: concrete

[bjshov8]

If you used quikrete then you had everything in the mix that you needed
except for water.
OTOH, too much water is the enemy of concrete.  The other enemy is improper
mixing and working the concrete too much after it is placed.  That is if you
put it down then keep smoothing on the surface, you will push the aggregate
down and end up with too much water and cement on the surface.

Concrete takes some time to develop strength, depending on the amount and
type of cement, and the temperatures.  Ordinary strength concrete will take
several days to develop a good amount of strength.  We normally take
strength tests at 7 days to get an idea of the concrete's quality, then
final strength tests are taken at 28 days.  The 7 day strength will be
approximately 70% of the 28 day strength.  Past 28 days the concrete will
develop a bit more strength but not a big percentage.

>  I poured 3 60lb bags of
> Quickrete concrete into an area that's about 3 square feet. I know that
> I managed to get some dirt and stones into the mix but I don't recall
> how much since it was getting dark and I don't have electricity in
> there yet. That slab has hardened but it doesn't seem hard yet; its as
> if the top layer could flake up if it scratched at it hard enough. It's
> also still a dark grey color. Keep in mind that I poured this slab on
> Sunday and it was still like this as of Tuesday.
>
> The directions only said to add water. Should I have added sand? Am I
> worrying about nothing? Did I add too much water?I have about 12 more
> bags left to pour to finish the job (area is about 20'x2.5') so I want
> to do the rest properly. Is the dirt a problem?