Column tubes.

Paper board tube concrete forms.

Ask.com gives an overview, but, I'm sure there are responders on CR4 who can tell you all about it.

Cheers

Here's the one I used for my porch. I made a rebar whatchamacallit with pieces wired together and put it in the tube just before pouring.

http://www.packagepavement.com/quiktube_use.html

Sonotube is one of the largest, there are others. www.sonotube.com

Most product questions can be answered on their website, sizes, shapes, finishes, ancillary products, etc.

Most common use of sonotube is in underground pours, so holding the tube in place is the easy part - the dirt does it for you. Drill your hole, drop in tube, plumb, backfill as necessary around tube, check plumb. Now build rebar cage, use plastic standoffs on the exterior of the cage to match to the sonotube diameter. Drop the cage into the tube with a crane. Using VERY thick concrete that will require vibrating. Add some, vibrate. Add more, vibrate. Use extreme care not to over-vibrate which would either float the tube or blow out the bottom. Continue adding concrete, only vibrating what you add until top is reached.

Mostly my experience is with large pours, smaller pours are not as demanding and require less equipment, but the process is largely the same.

Above ground IS trickier, as you note; the tube itself must be secured. For this reason steel forms are usually used instead of disposable tube. The steel forms are scaffolded and anchored to the base the column is being built on.

Leveling the tops is standard survey technique and readily available out on the web. Stringline, waterlevel techniques lend themselves to do-it-yourselfers.

Good morning edignan. Thx for your post. It generates the following.

Is it not enough to specify f'c 3000 psi, or do I have to add a slump figure, or how do I get "very thick" concrete? I assume the very thick concrete is to assure a high degree of compactness of the product? My project is for 5 each 12" dia x 7.3' high columns, with the upper 2 or 3 feet above gound, setting on underground footings. In your opinion, would you consider this a "large" pour?

Also thx to lynlynch, TVP45, TexasCharley, and erector1.

Good morning again Mr. edignan. Thx again for a superb post. It precipitates the following.

I am the designer/specifier/engineer. The client is a well-respected contractor. I always like to specify a design so that if the contractor delegates the work to an inexperienced-type, the contractor can simply give him my recommended construction sequence/procedure.

He will not be able to use an auger because I have designed a square steel-reinforced footing for each (steel-reinforced) column. I do not know wether he has built a 100 of these or none. Since all but about 2 feet of the top of each column will be back-filled, I'm thinking the friction of all that earth on the sides of the sonotube will assist in minimizing blow-out, as well as supporting the sonotube walls. I'm also assuming he has a lot of experience working with concrete to already know about some of the issues you raise, i.e., such as vibrating, adding too much water, etc.

Since the site is only accessible from one side, I am certain he will order a pump truck for the concrete. How will I or the county inspector know if he is placing 3000 psi concrete? Who mandates a sample be taken? Who pays for the compressive test? Are these issues all taken care of by virtue of the fact that the contractor has to build to meet IBC '06? Should I specify vibrating in 12" lifts, or would this be taken as too much information/control? Since it will probably have to be pumped, can I assume the aggregate will only be the approximate size of pea gravel, and therefore have no problem going thru and around the main and tie steel? Thx again for your expertise.

Ah, I am relieved. Had I known I wouldn't have been so strenuous in my warnings.

The techniques I relayed to you are old-school, so in addition to being familiar with concrete properties, I would expect the selected to be familiar with the placement techniques.

Haven't done construction in years, but would assume the drawings are going to be reviewed by the city/county as part of the permit process. Anything novel or a departure from normal will catch their eye, and explanation will be required.

Queen Creek was very civilized, and when I threw plans in front of them, I actually got to go over the plans WITH them and address their questions. Very useful, also a good question answer time for me!

Knowing a bit more now, I would actually guess they will excavate to do the footings, use steel or wooden formwork for the columns, remove the forms and backfill around the concrete. The sonotube material isn't actually strong enough to resist backfill pressures, and there wouldn't be much in the way to anchor them. Think large paper towel tube.

If this was a state contract job, the prime for the contract would pay the state the cost of an inspector to both slump test the mud before pour, as well as take many cylinder samples, ensuring some from each load. The cylinder samples would then soak in water for some period to ensure uniform best case cure of the concrete, then they would be broken and an average established. Fail the slump and the load gets returned, fail the cylinder test and you better be prepared to demonstrate that the value they tested to is adequate.

The inspector would also show up on the job to visually inspect those portions of the job that are safety critical. So he would drive by to view the placement of the tie steel, and he will look for the rebar cage to be tied to the tie steel.

As for the placement questions, only those things you feel essential from a design standpoint need be addressed, especially where you do something new or innovative. I.E. If the drawing shows a rebar tie between the footing and the column, it would be trade knowledge that the tie steel has to go into the footer prior to set, or the footer will be drilled for steel insert after. Up to you to actually show the mechanical tie.

Not my field again, but I would address in the drawings design elements (if any) not directly addressed by the IBC. So depending on how far afield the design goes...

Most of what you describe sounds like it is covered under the IBC. I am pretty sure the rebar layout is.

As for the quality control, on a civil job, lots of this will be specified by the city signing the drawings off. They will specify for instance, inspection prior to closing walls. So after the framework is up, the electric in, any plumbing in, you stop and call the inspector. After you have been green tagged, the crew can put up sheetrock. I would expect your contractor to establish what those inspection points are coordinating with the city inspector, and then arrange to have the city notified when those inspections are to be performed.

Thanks to the downturn, inspectors are lots easier to get to the job.

Good afternoon, edignan.

Yes, he will present the drawings and any other required documents to the county in the process of obtaining a permit.

In accordance with your suggestion, I will not be concerned about what method he will use to construct the columns, wether steel or sonotube. I will assume he has a certain amount of experience with this phase of construction, and will use the one that will be the most successful; and that he knows he will be responsible if there's a problem caused by the method he chose.

On the drawings, I have shown an L-shaped rebar to be cast in the footing for each of the 6 main steel rebar in the column; with 40 diameters of overlap. I think this is the mechanical tie you refer to.

I have enjoyed learning from you.

The "L" rebar should be sufficient, county will let you know if they want more.

As to the rest...

sometimes better you leave methods to the guy responsible for carrying them out, unless you had a specific need. All you do is pick up liability by being more specific.

Pleasure for me too, didn't realize I remembered so much from so long ago

Hello edignan:

Extremely good and knowledgeable advice here! IGNORE at your own risk!

A GA to you sir. For the good advice. And for one of the longest posts, ..............I have not written myself!

To all that read.............Hope you had a good Xmas!

I recently bought 4 tubes. Purchased from CMS in Austin TX. I bought 2 pair. 12" inner/outer and a 14" inner/outer. Cost about $30 USD each.

That is all I can help you with. They were not purchased for concrete. Completely different use than they were intended.

THEY ARE CALLED SONOTUBES

Flyinghigh, Enigman, and others,

Good discussion. If the general contractor and subcontractor both know that you will be doing a slump test as well as taking samples for subsequent compressive strength tests, they will be much less tempted to cheat on this phase of the work. 3000 PSI is a fairly conservative minimum strength of concrete. Just make sure that the concrete supplier knows it is going to be pumped and work with a reputable pumping company. Typically, you lose about 1" of slump in the pumping process, so you want to start with a little more slump than you expect at the delivery end of the pump hose (I would start near 6"). You will also lose about 1/2 cu.yd. of concrete into the pump and its piping, so you must allow for this excess in the concrete order.

Specify the compressive strength you want, at the slump you need. It takes very little water to supply the chemical reaction that makes portland cement into a strong material. Any extra comes at a cost in strength. Many additives exist to increase the pouring ability of the concrete (increase its slump). They usually are called plasticizers. Add a gallon of water per yard to a well-designed mix?--decrease the compressive strength by 20-40%. Add two gallons, and its near worthless although the guys finishing it may love how well it flows.

Talk with the concrete supplier and ask what they recommend you specify. This includes the aggregate size, any use of fly ash, slump, etc. They have a number of standard mixes which are suitable for the environment you are in and probably will choose one of these for you.

Write your specifications so that the contractor takes all responsibility for costs involved and losses involved to other trades if the installed concrete tests at less than the specified strength. Ensure that they uderstand that they will have to tear it out and replace it if it fails. Insist on a performance bond, if you have any doubts as to the contractor's reliability. Be willing to pay a little extra for a good contractor who is willing to do it right.

Regards--JMM

Good morning, jmueller. Thx for your participation.

Who requires the slump test, the engineer or the county? If by the engineer, would it be on the drawings? How much slump do I need for a particular job? I note your 6" recommendation for this project, but what about others? Would a logical requirement be "a 6" minimum slump test shall be taken immediately before delivery, and a 5" minimum slump test prior to each of the 5 columns pour"? (Based on info garnered from the concrete supplier?) I suppose we have to assume the supplier tested and the concrete met the 6" requirement at his location. Then, who checks the slump at the site? Is there a small report generated by the delivery guy? Does he have the tools and expertise? How does he know a slump test is required? Will the supplier automatically add the proper plasticizers?

The only thing I found in my "Concrete Masonry Handbook" is that slump is not specified in any code, standard, or specification. It goes on to say the desired slump is 8" for units with low absorption, and 10" for units with high absorption (obviously referring to CMU's).

I assume if 3000 psi concrete is called for, the contractor will order 3500 psi, just to be sure it meets the job requirements. Is this a reasonable assumption? If the compressive tests come in a week after the columns are built, and they failed, would the contractor expect the supplier to reimburse him for the expense to tear out the columns and replace them? Or would the contractor's performance bond (which is insurance?) pay for demolition and replacement?

When the contractor calls for delivery, will the supplier remind the contractor he will lose ~1/2 yard^3 in the pumping process, and to allow for this in the quantity he orders?

I will call the local concrete supplier later today.

Flyinghigh,

I know of no code requirements for a slump test, but they may be buried in the ACI 318 standard that the codes refer to. There are many related factors in dealing with concrete mixes--workability (slump, amount of vibration, voids, undesirable uplift), water content (workability, strength), plasticizers (slump, setting time) cost (. . .) etc. Since extra water sharply decreases strength plasticizers are used to increase workability. I suggested a slump of 6" because it is in the middle or slightly upper middle of the range of slumps and would give a very workable 5" slump at the discharge end of the pump hose. You can still do a good job with a discharge end slump as low as 3" but more vibration would be needed. If you specify a minimum 5-6" slump that would be a good point to begin.

Pumpers add water and plasticizers to the pump hopper to make filling the pump hose easier, so the first 2-5 cubic feet of concrete pumped has to be to a waste pile before the hose is moved to be over the first column form. (It is quite easy to see when the concrete leaving the hose is "OK" or free of the added water etc.) I suggest testing the slump directly from the truck before the pump hopper is filled. It should be as specified by you without any addition of water. This test would normally be done by the concrete contractor and witnessed by an owner's representative or the general contractor's representative. That should be the only time the slump needs testing. I suggest taking samples for compressive strength testing from the discharge end of the pump hose after filling the first pier and at the start of filling the last pier; two samples each so you can do 7 and 28 day tests. My experience is that the delivery driver is not responsible for any testing, but is responsible for adding any requested water or other additives and will document all such additions on the delivery forms. Those drivers are pretty smart, but usually keep in the background. When the mix is ordered, and you have specified the strength and slump, the supplier will check for any desired additives such as air entrainment or special cold-weather treatment (such as hot water), but will probably automatically include the necessary normal (not super-) plasticizers. Ask them about this.

Responsibility for replacing bad concrete will depend largely on who caused it to be weak. If the contractor demanded the addition of water on site, then probably the contractor will be held responsible. If none was added, then the supplier cannot avoid responsibility. The contractor is responsible for determining how much concrete is required, so he/she needs to include any extra for the pump or waste. The pump operator is responsible for having functional equipment and accessories and can advise the amount of concrete that equipment will add to the total order.

One other thing--I suggest that you plan some place for any extra concrete to be put. The delivery truck driver will take it back to the plant if there is no local place for dumping it. They will strongly prefer a local place to wash-out the truck, but this can be discussed prior to placing the order if no local place is reasonable. The ready-mix companies have places at their batch plants for wash out as needed, and the truck driver can add extra water to the mixer drum to delay any setting of the unused mix prior to his return to the plant. The pump operator will need a place to pump out the extra concrete remaining in the pump hopper and piping after the pour is finished. If the amount ordered is very close to the amount needed, he may put a sponge in the hopper and follow it with water, to push the last amounts of concrete out to the pour. I've had this done a few times! You may be able to plan a part of a sidewalk or exterior entry landing or air conditioner pad or other item which can be framed and prepared for the use of any extra concrete at the end of this pour.

Have you ever read the portland cement association's "bible", the Design and Placement of Portland Cement Mixes? It's helped me a lot.

--JMM

Good answer and a great resource!

Good morning jmueller. Thx for your note.

I could not find any reference to slump in the ACI 318.

I noticed Amazon dot com does not stock the Design and Placement of Portland Cement Mixes, but does sell the "...Guide to Concrete Homebuilding Systems". Are you familiar with that one?

Flyinghigh,

Nope; never saw that book. I got my copy of the Design... book from a local concrete mix vendor's technical sales staff (free!). I suggest the same approach for you; they may have a spare or be able to get you source and cost data.

I have worked with three brands of Insulated Concrete Forms (ICF's) for residential construction, and find them to be very worthwhile. I am open to discussion about the relative CO₂ contributions over the life cycle for various types of residential construction, if anyone wants to start a blog on this.

--JMM

They're called sonotubes

Tubes come in many sizes. You can measure your tape with a sight level or transit from each base to the desired level and cut each tube to the correct length. You should have had some rebars in the foundation sticking up where the tubes are intended to be. Attach the rebar for the tubes to these and assemble the rebar structure as pumb as possible. I imagine you will be putting something on top of these piers and they will need to be secured. Usually a grid support structure is fashioned for the tops of the piers to hold them plumb. Likely you will have bolts sticking out for securing the overhead structure. These should be tied to the rebar strucure and to the overhead support system (temporaily) during the pour and while the concrete sets up. Make sure everything (bolts relative to each other) is properly positioned and secure as pouring the concrete can induce some jolts. Use a wood structure at the base of the tubes so they don't shift up against the rebars. This must be the case at the top as well. Double check everything before the concrete leaves the plant.

Good morning Mrgreentoo. Thx for chiming in.

Yes, I have an L-shaped rebar coming out of the footing for every main rebar in the column, with 40 diameters of overlap. The columns will support GLB's. The details of the connection I left to the contractor (and the county inspector). I know generally welding on rebar is a no-no, but if I were him, I'd devise a way to weld the anchor bolts to the main rebar, to facilitate pouring of the column, without having to worry about dislodgement of the anchor bolts.

Sir;

60 years experience in building, mostly for my own account....ie: where I had substantial equity in the final product to be "wallet concerned" ten plus years after completion has given me multiple tries/experience.... ways of footing designs.

Following all the posts to this time I find one footing method not mentioned (maybe too late to use if planning has processed too far).

I've built shopping centers, industrial parks, 50,000 sq. ft + single free standing buildings down to 1500 foot single buildings and many multi tenant type commercial/industrial complexes, 5 acre to 20 acre land sites.

My choice...based on using many methods...is friction pile footings..[subject to soil quality tests].

If you have any knowledge of this technic.....or if not, it may be worth learning for future consideration.

I am sure you are familiar with driven piles............friction piles are VERTICAL auger bored holes that depend on the side friction of the set concrete (properly reinforced with re bar cage) after natural curing,

Ever try to pull an old post out of the ground? Tough to do.........same applies to the top load of the friction pile.......no need to "bell" it at the bottom.

I am Southern California born and raised....earthquakes are part of our design code/scheme......been through a lot of them. I have had no earthquake/footing damage to anything I have ever built.

My forever plan is

THE CHEAPEST WAY TO INSURE STRUCTURAL INTEGRITY, MAKE AN OVER SIZED HOLE AND POUR CONCRETE IN IT...ANY SHAPE THAT FITS YOUR DESIGN.

Especially if you can avoid below ground forming work hazards and time. if soil is not optimum two piles with a tie cap, properly separated, will increase dead load capacity or...... larger diameter will increase circumference surface area and load capability of any pile.

Only experienced problem is too high groundwater which precluded use of this type design........de watering was not an option.

Rocky ground and "Sugar sand" would also preclude use, but all of these are "no no's" FOR ANY PILE USE......

With a "Deputy Inspector" we could auger a hole, move to the second hole and with ready mix truck standing by pour the first hole while the second one was drilled. Reinforcing cage, per our tough codes, seldom require cage in any more than the top 25% of the hole depth, making proper cage placement insertion when within a reasonable suport distance from top of hole, in wet concrete.....then continue the pour.

This method is superior, in my opinion, for any job where piles are appropriate. Works wonderfully with concrete tilt up panel design building. AND A RIDGID STEEL FRAME DESIGN. A small grade level reinforced mini pad to accommodate panel/leg seats when needed.

Get data.......calculate it out.....it will surprise you..........

ALL MY DRILLINGS ARE AUGER, NOT BUCKET, DRILLED.

ECONOMICAL.......FAST...........STRONG.

MR. GUY

Good morning Mr. Guy. Thx for tossing your hat in the ring.

I'm interpreting your "friction pile footings" to be those made by augering a hole, then using sonotube only for that portion that protrudes from the earth? How much does a soil quality test cost? How can one become qualified to test the soil? Because on most of the jobs I've done, I would almost bet $ the soil will support vastly more weight than the 1500 psf limit the IBC calls for unknown soil strength. Which would reduce the footing design and associated costs.