Concrete curing for a ballast weight

[Camo]

I just poured my 35 gallon drum for my ballast weight yesterday and have it setting in my garage to dry. How long should I wait before using it? I used three 80lb bags.

 

[Treemonkey1000]

It starts setting pretty fast. Kinda depends on temps in the garage. If it is in a drum does it matter? The concrete is going to stay in the drum isn't it? From what I understands 24-48 hours for a reasonable cure. A week for thick pours and then it just keeps getting harder for about a year. At least that's what I thought.

 

[Gamemaster]

Keep it wet for awhile, spray water on top. If the top dries faster than the
center, it break-up it time and you will have alot of loose pieces on top.
You can still use it after 48hrs, but keeping it moist will make it last longer.

 

[RonMar]

Yep, keep it moist/use plastic on top to control the dry out process. If it is not structural, IE: the concrete is just setting there like a barrel full of sand and does not provide any of the support, then 24-48 hours sounds OK. If it is part of the structure, such as a crossbar passes thru the concrete, or the concrete keeps the sides of the barrel from buckleing, then I believe 28 days is the magic number to achieve the lions share of the concrete structural integrity.

 

[Camo]

Like this but smaller. The crossbar connected to the top link with steel, but the concrete hangs on the framework, inside the barrel.

 

[hawghead]

7 days concrete will achieve 50% of rated strength - 28 days to achieve full strength. Most of the time concrete will be well above 50% after 7 days using the cylinder test method. I say good to go after couple of days but to be safe wait seven days before subjecting the concrete to movement.

 

[builder2]

Zactly.

 

[Camo]

Thanks guys! I'll wait for the 7 days.

 

[alchemysa]

Thanks guys! I'll wait for the 7 days.

I recently made a small garden roller by filling a 20 litre paint drum with 'fast setting' concrete. I set a 1'' pipe through the middle to provide a tube for the axle shaft. I then let it sit outside for two weeks during a heat wave. I was amazed when i returned to it that although the top was hard and dry, the inside of the can was still damp and much of the concrete had not set at all (and probably never will now). I don't know what went wrong. Maybe I made it too wet. Maybe the cement was crook.

But I guess I'm saying be careful of keeping it too damp. Its in a drum and its going to stay pretty damp without adding water or keeping it covered. I believe concrete sets by a chemical reaction, not by drying out, but perhaps if its kept too wet for too long it stuffs up the reaction - unless its that special concrete that sets underwater.

 

[ray66v]

Too much water does make it hard to set, and often reduces strength. Use the minimum amount of water it takes to be able to mix & work concrete.