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Old 09-15-2013, 10:15 PM   #1
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Too much water in concrete


I built a wooden pedestal to hold a meter socket box. The pedestal is two 4x4 posts with 1x6 deck boards running between the posts. There are five deck boards on each side of the top of the pedestal, so that's where all the weight is.

I used a post hole digger to dig 36" deep holes for the posts. I dropped the pedestal into the holes and mixed some concrete. I mixed up a couple 60lb bags of Sakrete per the instructions, which had me adding 2.5 quarts of water per bag. (I didn't have a way to measure quarts, so I converted this to cups, which is 10 cups.) The mix seemed really dry, but I went ahead and filled the holes. There was only enough concrete to fill the holes 3/4 of the way. I mixed one more 60lb of Sakrete, but I ended up adding 16 cups of water by accident. (Don't ask ) The mix was very watery, but I was out of concrete and out of sunlight, so I went ahead and topped the holes off. The watery concrete was a helluva lot easier to work with... lol.

I know concrete loses strength when it's too watery, but given the situation, should I even worry about it? This obviously isn't structural and the concrete is just holding the pedestal plumb and keeping it from falling over. The watery concrete actually helped out a bit because the posts were not perfectly centered in the holes. They were closer to one side of the hole, so it was difficult to work the drier concrete into that space. The watery concrete just kinda flowed into that space. So what do you think? Will I be good, or is my concrete eventually going to crack and pedestal fall over?

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Old 09-16-2013, 05:08 AM   #2
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Too much water in concrete


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Originally Posted by powertoolguy View Post
I built a wooden pedestal to hold a meter socket box. The pedestal is two 4x4 posts with 1x6 deck boards running between the posts. There are five deck boards on each side of the top of the pedestal, so that's where all the weight is.

I used a post hole digger to dig 36" deep holes for the posts. I dropped the pedestal into the holes and mixed some concrete. I mixed up a couple 60lb bags of Sakrete per the instructions, which had me adding 2.5 quarts of water per bag. (I didn't have a way to measure quarts, so I converted this to cups, which is 10 cups.) The mix seemed really dry, but I went ahead and filled the holes. There was only enough concrete to fill the holes 3/4 of the way. I mixed one more 60lb of Sakrete, but I ended up adding 16 cups of water by accident. (Don't ask ) The mix was very watery, but I was out of concrete and out of sunlight, so I went ahead and topped the holes off. The watery concrete was a helluva lot easier to work with... lol.

I know concrete loses strength when it's too watery, but given the situation, should I even worry about it? This obviously isn't structural and the concrete is just holding the pedestal plumb and keeping it from falling over. The watery concrete actually helped out a bit because the posts were not perfectly centered in the holes. They were closer to one side of the hole, so it was difficult to work the drier concrete into that space. The watery concrete just kinda flowed into that space. So what do you think? Will I be good, or is my concrete eventually going to crack and pedestal fall over?
It will be fine and we should be glad the 1 inch slump mix is below grade. Concrete people have run " the dryer the stronger " into the ground, so to speak, to the point of ridiculous.

Possibly it is but the bag also should state that for most DIY home owner projects a 9 inch slump will be just fine and as you found much easier to work with. Leave the stiff mixes to the pros that have the experience, tools to work with and a state inspector leaning over their shoulder checking every batch for slump as the bridge is built.

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Old 09-20-2013, 09:27 AM   #3
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Too much water in concrete


You're fine, it it's holding up a bridge.

Fairview is correct somewhat about the dryer is better myth, the strongest compression test I ever did broke at over 11,000psi on what was basically slurry water. But that had a ton of chemical in it, whereas the Qwikrete is just basic concrete.

But again, don't land any 747s on it and you'll be fine.
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Old 09-20-2013, 10:15 AM   #4
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Too much water in concrete


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Originally Posted by Mort View Post
You're fine, it it's holding up a bridge.

Fairview is correct somewhat about the dryer is better myth, the strongest compression test I ever did broke at over 11,000psi on what was basically slurry water. But that had a ton of chemical in it, whereas the Qwikrete is just basic concrete.

But again, don't land any 747s on it and you'll be fine.

Not a myth at all but a proven fact,and just because somebody makes a statement about 9 inch slump concrete being okay to use for a home owner project doesn't make it true,and is just talking through his hat.

Would you let someone pour a driveway at your house at that slump,i think not.

6. COMPRESSIVE STRENGTH OF CONCRETE
The strength of concrete is controlled by the proportioning of cement, coarse and fine aggregates,
water, and various admixtures. The ratio of the water to cement is the chief factor for determining
concrete strength as shown in figure1. The lower the water-cement ratio, the higher is the
compressive strength. A certain minimum amount of water is necessary for the proper chemical
action in the hardening of concrete; extra water increases the workability (how easily the concrete
will flow) but reduces strength. A measure of the workability is obtained by a slump test.
Actual strength of concrete in place in the structure is also greatly affected by quality control
procedures for placement and inspection. The strength of concrete is denoted in the United
States by
f'
c
which is the compressive strength of test cylinder 6 in. in diameter by 12 in. high

measured on the 28th day after they are made.
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Old 09-20-2013, 10:46 AM   #5
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Too much water in concrete


Quote:
Originally Posted by Canarywood1 View Post
Not a myth at all but a proven fact,and just because somebody makes a statement about 9 inch slump concrete being okay to use for a home owner project doesn't make it true,and is just talking through his hat.

Would you let someone pour a driveway at your house at that slump,i think not.

6. COMPRESSIVE STRENGTH OF CONCRETE
The strength of concrete is controlled by the proportioning of cement, coarse and fine aggregates,
water, and various admixtures. The ratio of the water to cement is the chief factor for determining
concrete strength as shown in figure1. The lower the water-cement ratio, the higher is the
compressive strength. A certain minimum amount of water is necessary for the proper chemical
action in the hardening of concrete; extra water increases the workability (how easily the concrete
will flow) but reduces strength. A measure of the workability is obtained by a slump test.
Actual strength of concrete in place in the structure is also greatly affected by quality control
procedures for placement and inspection. The strength of concrete is denoted in the United
States by
f'
c
which is the compressive strength of test cylinder 6 in. in diameter by 12 in. high

measured on the 28th day after they are made.
Rave on KINGFISH. Go back and read with comprehension rather than thinking what you want to say after reading the first few words.
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Old 09-20-2013, 12:28 PM   #6
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Too much water in concrete


No question about lowering the compressive strength of concrete plus it causes more cracking. - In this case the even with a high slump with many, many times stronger that the dirt and other materials in the hole. - It all depends on the application.

For a driveway, it is obvious that the slump must be 3" -4" for the puposes of placing and finishing. If you grout a concrete block wall on a 20 story building, you are not allowed to use concrete with a 3" slump, but need a wet grout with a 8" to 11" slump for best construction. - Again it all about the use and application.

Sometimes amateurs should not go blindly by some preconceived assumptions and should bother to think a little.
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Old 09-20-2013, 03:59 PM   #7
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Too much water in concrete


Exactly. "Concrete" is not a monolithic term, it encompasses a wide range of materials and mix designs, and should be engineered for anything more complex than filling a fencepost. That does not mean you need an engineer, it means you need to take into consideration all aspects of the use and requirements.
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Old 09-21-2013, 04:16 PM   #8
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Too much water in concrete


Quote:
Originally Posted by Canarywood1 View Post
Not a myth at all but a proven fact,and just because somebody makes a statement about 9 inch slump concrete being okay to use for a home owner project doesn't make it true,and is just talking through his hat.

Would you let someone pour a driveway at your house at that slump,i think not.
Regarding the statement I made, the myth "used" to be true, when concrete was made out of rocks, sand, water, and cement. Now, with mid-range and high-range water reducers, etc., one can greatly reduce the water/cement ratio while at the same time maintain a flowable plasticity. To pour PT decks, we would make a slump of a 9-10" into a 63m pump and 300ft of hose, just to get a 6-7" at the end of the hose. The cylinder breaks averaged 6800psi (over a period of 10 months, 2-3 times a week, consistently), which was 1300psi over spec. Water/cement ratio matters, slump doesn't (unless the aggregate segregates).

The other part of my statement was that he's just holding up a pedestal, so I think the concrete being less than 4000psi will be just fine.
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Old 09-21-2013, 08:52 PM   #9
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Too much water in concrete


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Originally Posted by Mort View Post
Regarding the statement I made, the myth "used" to be true, when concrete was made out of rocks, sand, water, and cement. Now, with mid-range and high-range water reducers, etc., one can greatly reduce the water/cement ratio while at the same time maintain a flowable plasticity. To pour PT decks, we would make a slump of a 9-10" into a 63m pump and 300ft of hose, just to get a 6-7" at the end of the hose. The cylinder breaks averaged 6800psi (over a period of 10 months, 2-3 times a week, consistently), which was 1300psi over spec. Water/cement ratio matters, slump doesn't (unless the aggregate segregates).

The other part of my statement was that he's just holding up a pedestal, so I think the concrete being less than 4000psi will be just fine.

Sure we've used water reducers for years,and years,and they just get better all the time,but when you talk about pumping,that's a whole new ball game,and different rules apply,and I understand and agree about the part about holding up a pedestal,the part I disagree with is the guy that made the statement about it being just fine for a home owner to use a 9" slump mix for what he described as home owner projects.
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Old 09-22-2013, 09:02 PM   #10
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Too much water in concrete


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Originally Posted by Fairview View Post
It will be fine and we should be glad the 1 inch slump mix is below grade. Concrete people have run " the dryer the stronger " into the ground, so to speak, to the point of ridiculous.

Possibly it is but the bag also should state that for most DIY home owner projects a 9 inch slump will be just fine and as you found much easier to work with. Leave the stiff mixes to the pros that have the experience, tools to work with and a state inspector leaning over their shoulder checking every batch for slump as the bridge is built.
And most DIY'ers are bound to fail if they take this advise seriously.........

They don't need to pour a 1" slump, but a 9" is oftentimes going to leave them with a far inferior product than say a 5". Most DIY'ers are already behind the 8 ball when pouring concrete, when compared to a pro that does it everyday, no reason to make it worse by placing concrete that's bound to fail on top of it.......

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