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-   -   Mixing my concrete or get it brought in (http://www.diychatroom.com/f105/mixing-my-concrete-get-brought-141267/)

darren 04-23-2012 08:30 PM

Mixing my concrete or get it brought in
 
I am building a deck and am going to need roughly .75 cubic yards to fill my holes. Is it better to get ready mix concrete or go to Home Depot and buy concrete and mix it myself.

joecaption 04-23-2012 08:35 PM

http://www.concretenetwork.com/concr...calculator.htm

darren 04-23-2012 08:44 PM

Thanks Joe that is the best calculator I have seen so far. Is it more worth it to mix it myself or to get ready mix.

joecaption 04-23-2012 08:52 PM

That's up to you to decide.
I'd call and see what it's going to cost. There going to hit you with a small load charge.

TRUEPRO 04-24-2012 06:40 AM

Are you using the concrete for the post holes? if so then def go buy the 80lb bags of quickcrete. This way your not busting your ass wheeling concrete to your back yard trying to get the truck out of there. 1 yd is the minimum you can order from most companies (titan, crmp) and your looking at 250-300$.

Also, you dont need wet concrete to build your deck. Fill the post hole up with 40lbs of dry quickcrete and put 1/2 of a 4" cinderblock on top of that. Tamp. The 4x4 post will sit on top of the block. The dry concrete will absorb moisture from the ground and harden over night. The weight of the deck will hold the post in place for life. Setting post in wet concrete is the old, less effective way.

dwcopple 04-24-2012 01:43 PM

Quote:

Originally Posted by TRUEPRO (Post 906126)

Also, you dont need wet concrete to build your deck. Fill the post hole up with 40lbs of dry quickcrete and put 1/2 of a 4" cinderblock on top of that. Tamp. The 4x4 post will sit on top of the block. The dry concrete will absorb moisture from the ground and harden over night. The weight of the deck will hold the post in place for life. Setting post in wet concrete is the old, less effective way.

Bingo! That is what I did too. hasn't moved an inch since. I built mine in april 2005.

CoconutPete 04-25-2012 08:38 AM

If you don't feel like doing all the labor of mixing it, you can always check to see if there is a short load place near you. I have this one near me which I kinda wish I had known about when I was building my deck: http://www.mobilemixconcrete.net/

You can also try to google "cart-away" or "kart-away" concrete. There is another place near me which does that, you basically show up with a vehicle that can tow and they fill their own trailer with up to 1 yard and you just take it home, empty it and return the trailer.

robertcdf 04-25-2012 06:25 PM

Quote:

Originally Posted by TRUEPRO (Post 906126)
Are you using the concrete for the post holes? if so then def go buy the 80lb bags of quickcrete. This way your not busting your ass wheeling concrete to your back yard trying to get the truck out of there. 1 yd is the minimum you can order from most companies (titan, crmp) and your looking at 250-300$.

Also, you dont need wet concrete to build your deck. Fill the post hole up with 40lbs of dry quickcrete and put 1/2 of a 4" cinderblock on top of that. Tamp. The 4x4 post will sit on top of the block. The dry concrete will absorb moisture from the ground and harden over night. The weight of the deck will hold the post in place for life. Setting post in wet concrete is the old, less effective way.

DO NOT DO THIS. This is a VERY BAD IDEA, yes the concrete gets "hard" but it WILL NOT get to design strength without the proper amount of water and proper mixing. Otherwise everyone would be doing this.

I order in 1 yd trucks all the time. 42 bags will cost you $160-200 plus delivery and it will take 1 person 1 full day to mix it all in a wheelbarrow or 1/2 day with a mixer. Whereas a truck will take 20 minutes to unload and cost $250-$300. I'll pay for the truck all day long so we can get back to work.

TRUEPRO 04-26-2012 01:56 PM

Quote:

Originally Posted by robertcdf (Post 907546)
DO NOT DO THIS. This is a VERY BAD IDEA, yes the concrete gets "hard" but it WILL NOT get to design strength without the proper amount of water and proper mixing. Otherwise everyone would be doing this.

I order in 1 yd trucks all the time. 42 bags will cost you $160-200 plus delivery and it will take 1 person 1 full day to mix it all in a wheelbarrow or 1/2 day with a mixer. Whereas a truck will take 20 minutes to unload and cost $250-$300. I'll pay for the truck all day long so we can get back to work.


This is true for 2 story decks but for a single story deck, post holes cemented in is a waste of time. And your your so concerned about it getting "hard enough"? I didnt know we were building a house on top of this deck. When was the last time you actually dug down there and checked how hard that cement is???? You obviously have no clue what your talking about and should not even be on this forum. Your supposedly a "deck guy" trying to act like you know what your talking about. I am a general contractor with 10 years in the framing trade and 10 in the masonry trade. I would never give DIY advice on this forum if i wasnt 100% sure about what im talking about.

robertcdf 04-26-2012 02:06 PM

Quote:

Originally Posted by TRUEPRO (Post 908145)
This is true for 2 story decks but for a single story deck, post holes cemented in is a waste of time. And your your so concerned about it getting "hard enough"? I didnt know we were building a house on top of this deck. When was the last time you actually dug down there and checked how hard that cement is???? You obviously have no clue what your talking about and should not even be on this forum. Your supposedly a "deck guy" trying to act like you know what your talking about. I am a general contractor with 10 years in the framing trade and 10 in the masonry trade. I would never give DIY advice on this forum if i wasnt 100% sure about what im talking about.

And you've been doing it wrong for years. It's ok, I've trained a few gcs how to build a deck properly, feel free to read the article I wrote for the professional deck builder magazine last year you might learn something too. While you're at it look up information about concrete and its design strength and how it's achieved.

Daniel Holzman 04-26-2012 02:56 PM

Before trash talking gets totally out of hand, a few comments. The use of dry placed concrete is very common in commercial and industrial construction. The common term is preplaced aggregate, and here is how it works. The contractor preplaces the aggregate (crushed stone) portion of the concrete at the location required. Then the contractor adds the sand/water/cement mix to the aggregate, and you get concrete.

You can use this technique in difficult locations, like under water, where of course you don't need to include the water in the mix. The idea of placing dry concrete and letting it hydrate is pretty interesting. I have never actually seen it done, except I ran a couple of inadvertent experiments in my garage with old bags of concrete mix that hardened over time due to absorption of moisture from the air.

I think the reason this technique is not common in commercial/industrial construction is the difficulty of achieving design strength, as the previous poster noted, because of the inability to fully hydrate the cement in the concrete. However, the strength of the concrete is never the limiting factor on a deck, the soil strength is always the limiting factor, unless you are on solid rock.

So my conclusion is there is an element of truth to both comments. If you need to achieve a specific design strength in a reasonable period of time, this technique is not for you. If you are not too concerned about the ultimate strength, which is the case for the vast majority of decks and similar structures, this technique sounds perfectly reasonable, and I like the out of the box thinking. Of course, you should run this idea by the building inspector first, since they may not like it, and your permit could be in jeopardy if you use this method and the building inspector rejects it later.

robertcdf 04-26-2012 07:04 PM

Quote:

Originally Posted by TRUEPRO (Post 908145)
This is true for 2 story decks but for a single story deck...

The OP never said how high his deck was, how would you feel if this was a deck 12' up and it failed during a party and killed someone?


Regarding decks relying on the soil this is a correct statement, however the concrete is used to transfer the load to the soil. The 6x6 post MUST disperse the weight to a larger diameter than just 5.5"x5.5" there is where a pier comes into play, the diameter of that pier is dictated by how much weight is on it (or is rated for it) and the soil bearing capacity. If the concrete crumbles the structure can fail, if the post is trying to transfer 4,000# and the concrete was just dropped into the hole the concrete has a high likelihood of failing.

Dan, regarding using "dry placed" concrete is NOT designed the same way as sakrete or quickrete that is available in the local stores, that is also designed by a professional with everything taken into account. I highly doubt a DIYer has the kind of knowledge to engineer that, if he did he would not be on here asking questions.

Daniel Holzman 04-26-2012 07:26 PM

I hear you, but consider this. A typical concrete mix has a strength of 3000 psi. The minimum sonotube diameter allowed in my town is 10 inches, which is about 75 square inches. This gives the typical sonotube a compressive strength of about 225,000 lbs. The greatest conceivable deck load on a sonotube would be perhaps 100 square feet, even this is beyond normal. Even assuming 100 psf, which is way beyond code, the largest post load would be 10,000 lbs. So your typical 10 inch diameter sonotube is going to support more than 20 times the maximum conceivable load.

So clearly the soil controls, since soil may have an allowable bearing capacity as low as 500 psf. So even if the dry place concrete technique achieves only 20 percent of design strength, it is likely way beyond what you really need. Hence for a single story deck, or even a two story deck, the limiting factor is going to be the strength of the soil, and the strength of the framing. So in this limited case, I look at this idea as one with merit.

robertcdf 04-26-2012 07:56 PM

Quote:

Originally Posted by Daniel Holzman (Post 908417)
I hear you, but consider this. A typical concrete mix has a strength of 3000 psi. The minimum sonotube diameter allowed in my town is 10 inches, which is about 75 square inches. This gives the typical sonotube a compressive strength of about 225,000 lbs. The greatest conceivable deck load on a sonotube would be perhaps 100 square feet, even this is beyond normal. Even assuming 100 psf, which is way beyond code, the largest post load would be 10,000 lbs. So your typical 10 inch diameter sonotube is going to support more than 20 times the maximum conceivable load.

So clearly the soil controls, since soil may have an allowable bearing capacity as low as 500 psf. So even if the dry place concrete technique achieves only 20 percent of design strength, it is likely way beyond what you really need. Hence for a single story deck, or even a two story deck, the limiting factor is going to be the strength of the soil, and the strength of the framing. So in this limited case, I look at this idea as one with merit.

Why is this method not in the local codes for deck construction?

TRUEPRO 04-27-2012 05:30 PM

Quote:

Originally Posted by robertcdf (Post 908390)
The OP never said how high his deck was, how would you feel if this was a deck 12' up and it failed during a party and killed someone?


Regarding decks relying on the soil this is a correct statement, however the concrete is used to transfer the load to the soil. The 6x6 post MUST disperse the weight to a larger diameter than just 5.5"x5.5" there is where a pier comes into play, the diameter of that pier is dictated by how much weight is on it (or is rated for it) and the soil bearing capacity. If the concrete crumbles the structure can fail, if the post is trying to transfer 4,000# and the concrete was just dropped into the hole the concrete has a high likelihood of failing.

Dan, regarding using "dry placed" concrete is NOT designed the same way as sakrete or quickrete that is available in the local stores, that is also designed by a professional with everything taken into account. I highly doubt a DIYer has the kind of knowledge to engineer that, if he did he would not be on here asking questions.

Well unfortunately i was reprimanded by a moderator for advising a DIYer to hire a professional for a particular project. Your right about making sure to be cautious when giving advice on this forum because there is always a risk for severe injury when attempting projects that normally are done by licensed professionals but in there end the joe shmoe homeowner is gonna do what their gonna so all we can do is say good freakin luck pal. Were not aloud to give advice that could prevent injury on this forum because the moderators think they know more about construction then us pro's. Oh well


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