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Site Preparation for Building a Grain Bin: a Discussion

Joy worked in construction for 7 years alongside her husband (25+ yrs. experience)—working on pole barns, grain bins, and barn repairs.

Varied Grain Bin Cluster

This grain bin cluster was assembled over several years' time, and includes bins of different eras and makes, with varying foundation requirements. Pits, drying floors, and other set-ups are included.

This grain bin cluster was assembled over several years' time, and includes bins of different eras and makes, with varying foundation requirements. Pits, drying floors, and other set-ups are included.

I Am Not a Concrete Professional!

I am not qualified to tell you exactly how the concrete ought to be mixed, poured, and finished. I can only tell you our experiences, and offer some tips for ensuring you get a good foundation for your bin. Before proceeding with your project, please discuss your intentions and requirements with a professional concrete contractor.

Work Cautions

A carefully poured cement pad ought to be formed and cured prior to erecting a grain bin. If you are familiar with cement work and understand the needed strength of such a slab, you may do this yourself . . . but be aware that an unstable or improperly installed foundation is a hazard. At best it may crack, and at worst it may damage your bin or cause accidents. A failed slab must be removed and repoured.

If the bin is being installed with a hopper or perhaps over a pit, the cement process is even more exacting.

Below you will find pointers on getting the best foundation for your bin.

Site Considerations

  • Stable ground
  • Room to maneuver and park trucks and large equipment during construction, which will not interfere with regular traffic patterns
  • A place to dump dirt left over from leveling the site
  • Permanent driveway(s) for filling, checking, and unloading bin(s)


Equipment and Skills Required

  • Earth moving equipment and responsible, experienced operators
  • Knowledge of building site preparation methods
  • Properly layed cement forms, including extra reinforcements
  • Competent professionals with excellent concrete working and finishing skills
  • An understanding of stresses and weight limits
  • Abundant common sense


Concrete Professionals Needed

Specifications for your slab may vary from the norm for a regular building foundation, as a grain bin foundation needs to be extea tough, able to withstand enormous pressures and stresses from weight, moisture, wind, and other factors.

All preparations for the foundation should be undertaken by a professional, or at least someone whose experience you trust in these matters.

The site must be scraped and levelled, then sand or gravel must be brought in, and the concrete form(s) set. All forms must be level and properly squared.

The concrete must be poured, leveled, and worked fairly quickly. This is not the time to teach an amateur how to form and finish concrete.

All natural conditions under which the bin(s) may be used or their contents checked should be considered when deciding how smooth a finish you want your slab to have.

Summary of Ground Prep

A tractor with a bucket or a front-end loader will probably be needed to scrape and level the site.

Depending on your soil composition, terrain, and special problems, you may need to remove rocks, fill in slants or low spots, compact and settle the ground with a roller, or dig out roots.

Builders sand or gravel will need to be hauled in and spread to create a suitable underlayment for the concrete.


Dirt Pile From Leveling Process

The dirt removed during site prep was moved to the edge of the big driveway, away from grass and out of the way of traffic patterns.

The dirt removed during site prep was moved to the edge of the big driveway, away from grass and out of the way of traffic patterns.

Weight Specifications for the Pad

A concrete pad on which a single 18-foot diameter, 6 ring bin without a hopper is erected must hold over 100 tons when the bin is filled with wheat (for example). This is only a 4,000 bushel bin.

Discuss your needs with your ready mix provider, and talk to other people who have done what you're trying to do, and are happy with their results. Make sure your concrete crew understands exactly what you want to achieve, and that they have the experience and tools to make it happen.

There are various ways of reinforcing the most crucial areas of a slab, whether or not a bin is placed on a hopper. A common method involves a grid of rebar embedded in the concrete.

Manoeuvrability

Besides the earth moving equipment, you must plan for the machines you will use while building your bin.

If you are intending to use a crane or boomtruck to lift your bin during construction, you will need to leave plenty of room to manoeuvre, including taking the partially erected bin off the site if you need to block it in during off-hours.

Preparing a Site for Concrete

Preparing a Foundation for a 20,000 Bushel Bin

Reinforcement Methods for Use With Hoppers

One method involves building a gridwork of rebar, wired together at right angles, with crossbars no more than 8 inches apart. This frame is dropped into a hole 4 feet deep and about 2 feet across. There is one hole per hopper leg. The holes are then filled with concrete, and the remainder of the pad is poured thicker than normal (8" minimum), and of an especially strong mix (we've used fiber mesh). The concrete is worked and finished as usual. You will want a chop saw with an appropriate metal-cutting blade to cut the rebar sticks to length on the jobsite.

Another method uses steel barrels filled with concrete, and dropped into holes only slightly larger than the barrels.

Similar to this are 3 foot by 3 foot holes which are filled with a stronger than average mix of concrete.

Criss-crossing the whole slab with steel rebar is a typical way of reinforcing a bin fpundation, as in the video above. If you use this method with a hopper, we recommend using a tighter, even stronger grid reinforcement, as well as fibermesh concrete and one of the extra methods just desribed.

However, none of these methods are foolproof.

Captions for the above photos:

  1. This is a small bin used for storing grains for feeding to animals. It has a 200 bushel capacity, which is 10,000 pounds in weight when dealing with heavier grains such as wheat.
  2. The bin and hopper were erected on top of steel barrels cut in half and filled with concrete.
  3. Here are the barrels ready to be moved from a truck bed and lowered into prepared trenches.
  4. Careful measurements were taken to ensure that the bin would be level and centered on all four barrels. The iron bars are merely being used to square up the barrels.
  5. Two barrels are in place, with the other two ready to be moved in.
  6. Three barrels are checked in different directions for accuracy of placement.
  7. Angle iron guides, which will be used to anchor the hopper feet, are used as the bin is tilted into place.
  8. A flatbed truck with a hoist is used to set the bin onto the barrels.

Failures

These are the methods we have used most often, but have had variable results as to the integrity of the concrete pads. In one case, the pad cracked, apparently due to excessive weight from overfilled bins. In another case, erosion and runoff caused shifting of the pad. In both cases, a crane was brought in to lift the bins off the pads, then the slabs were jackhammered out, and repoured.

Water Patterns

Low spots need to be corrected prior to laying out your building site.

Low spots need to be corrected prior to laying out your building site.

Special Problems to Look Out For

Runoff and underground water flow must be carefully observed prior to deciding the final placement of your slab. Don't pour a foundation where you suspect water, sinkholes, or other natural flaws may be a problem. Even occasional pooling or light flooding may shift the pad.

Of course, trees or other plants with invasive roots close to the surface must be avoided.

Adequate room for a driveway next to the slab must be included in calculations, as must other traffic patterns, whether existing or anticipated.

Pits

A young work crew in training installs steps made of bent rebar around the perimeter of this pit, using a cement drill to prepare holes in the old concrete.

A young work crew in training installs steps made of bent rebar around the perimeter of this pit, using a cement drill to prepare holes in the old concrete.

Grain Bins Over Pits

I cannot tell you here how to build a bin over a pit, but you should be aware that this is an option. This structure comes with many of the same problems as any other below-ground structure, including basements.


Pouring a Grain Bin Footer

Foundation Variations

Grain bin foundations vary widely in their dimensions and integrity, and in the materials used.

During different eras, what was needed has not always been the same. Older grain bins are frequently smaller than many modern bins. Consequently, the weights which they and the foundations carried were less.

Below you will find a sampling of foundation styles and ideas.

Accessibility

A good approach to your bin(s) for filling and unloding is essential. Plan for the biggest trucks and trailers you foresee using or hiring.

More Info Planned

I was hoping to add more photos and specific info on reinforcements for bins with hoppers. But my fact-checking process has been delayed, so I chose to go ahead and add bits as I am able.

Please do not contact me for advice on your grain bin project, as I am unlikely to be able to advise you beyond what has been provided here and in related articles.

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This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2020 Joilene Rasmussen

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