It’s winter and I just got back from the mail box and noticed one of my driveway slabs has heaved. This in addition to a sidewalk section that has moved too. I noticed this last year about this time, so what gives?
Frost heave. The differential in moisture content in the soil as it freezes causes the sections to raise at differing rates. The same thing can happen in the summer if you have expansive soils like clay. As they uptake moisture they expand as much as ten percent!
I’m kicking myself, I noticed the expansion joint needed to be caulked this fall but didn’t get around to it. Most of the time the slab will settle back down just fine but occasionally as that section is heaved additional material works itself under the slab and it doesn’t drop.
Caulking joints, using a concrete sealer and controlling water runoff are preventive steps that can and should be taken to minimize slab heaving.
If your concrete is not how you would like it call the concrete raising and leveling professionals today,
Do you have slabs that seem to rise and fall with the seasons? Then you are likely dealing with expansive soils, in our area, generally clay. Much of the United States has expansive clays to a greater or lesser degree.
In a typical year in the United States, expansive soils cause a greater financial loss than earthquakes, floods, hurricanes and tornadoes combined.
Clay in and of itself isn’t the problem, the problem is the change in moisture content. If the moisture content stays the same no swelling or shrinkage will happen. In Washington State, and in particular Easter Washington, we have four seasons where we can expect cold wet winters followed by warm dry summers.
When we combine expansive soils and wet winters followed by dry, hot summers, heaving and settling are to be expected.
I personally have one section of my driveway that magically rises from the ground about 3/4″ each spring and as the ground dries, settles back down. Not surprisingly it is on bare soil with no gravel bed.
Some people call to tell us their slabs used to rise and fall, but now they are staying up, why? First let’s try to eliminate the issue. In my case the section that rises and falls is the lowest of six driveway panels, water seeps between the expansion joint when it rains or snow melts, (I really should seal that joint) saturating the underling soils causing expansion. As the summer heat comes on, the soils dry allowing the slab to settle. To reduce heaving and settling, seal all expansion joints on your concrete. A good, inexpensive product is Sika brand (Home Depot) or Quickrete brand (Lowes) polyurethane caulking.
If slabs are not resettling as they used to, then two issues may be in play; first, debris washes under slabs which cause the slab to remain high, this is very common. Second, you may be over watering your soil keeping it saturated and swollen.
When expansive soils shrink, fissures can open up which allow water to run off and carry away soils, causing settled concrete slabs along with cracked and damaged driveways, porches and patios.
The key to building on these type of soils is to insulate concrete as much as possible from the soils. Gravel should be used as a foundation in the construction of driveways and walks. Caulking along seams and joints and along foundation walls minimizes water penetration under slabs and, especially important to basements, making sure concrete slabs are not settling toward foundation walls draining water along the basement walls.
If you have sunken and settled concrete call the concrete raising and leveling professionals 1-855-752-2522, for a no cost, no pressure estimate to have your damaged concrete raised back to proper grade, using state of the art Geo-Polymer injection technology.
Superior equipment, superior Polymers, superior Training, producing superior results.
Pools, what a great way to spend a lazy summer day. Kids and Grand Kids enjoying the water, friends over for a pool party as you BBQ Ribs or Burgers, or just a relaxing evening enjoying the crystal clear water as the sun goes down. Having your own pool is a dream come true for many families, one that can build unity and be a gathering spot for family and friends for years, even generations to come.
Then there is the cost and hassle of chemicals and maintenance, all of which pales compared to the nightmare of settling pool decks. At 1-855-752-2522 we’ve about seen it all. Here are some things to know about settled pool slabs;
How we approach settled concrete slabs around pools varies with the type of pool, be it Gunite, Fiberglass or Vinyl.
Let’s first discuss Concrete or Gunite Pools; these pools have the most robust construction of the three and are considered the safest to work on, having been constructed of a special concrete reinforced with rebar.
Typical deck construction on Gunite pools is to lay the deck over the top of the vertical wall of the pool, which is then caulked with waterproof pool caulking. This method leaves a very clean look with no bullnose tile to be found, though for aesthetics they can be used.
Settling occurs two ways. First, over time the caulking seal fails, allowing water penetration which leads to the compaction of fill dirt under the deck and along the walls of the pool, which over time, caves the soil in toward the pool and gradually leads to “pivoting” of the concrete deck.
The second area is on the outer side of the deck, where the deck meets grass. This settles slightly as water saturates the soils along the edge of the deck and grass junction. As this settles ever so slightly the slab pivots, opening up the caulk line allowing water to again, penetrate and further saturate and compact soils.
We have two good views and a video of a pool deck “pivoting” at www.SlabjackGeotechnical.com in the before and after pictures section as well as in the video section.
The diagnosis – if we were to completely lift the slab off the side of the pool you would find large voids along the pool, with the largest at the edge of the pool, even though the settling appears to be on the opposite, or grass side of the deck.
The cure – while the safest of the three, due to its robust construction, Slabjacking can exert tremendous pressures, thousands of pounds per square foot in some circumstances, not something we wish to have against the side of a pool. 1-855-752-2522 uses a hydrophobic Polymer (waterproof) that is injected and allowed to flow into the voids along the pool, consolidating loose soils and filling voids. This Polymer is very light, only four pounds per cubic foot but extremely dense so it is much safer than pumping a slurry which weighs between 100-140lbs per cubic foot against your pool. After these voids are filled any settling is taken care of on the opposite side of the slab.
Fiberglass and Vinyl pools are much less robust and as such, are approached much differently than concrete/Gunite pools. Due to the flexible nature of Fiberglass, and especially Vinyl pools, we do not attempt to fill voids along the vertical walls, doing so could bulge the pool walls and there would be nothing we could do about it after the fact. We will raise decks settled toward these pools only after extensive testing and then only with a disclaimer in the contract. Decks settled away from these pools are generally safe to raise and pose minimal risk of damage to the pool itself.
When it comes time to raise your pool deck call the concrete raising and leveling professionals 1-855-752-2522. Whether a Residential, Commercial or a Municipal pool, Slabjack Geotechnical is the right call – superior Equipment, superior Polymers, superior training, produces superior results.
Home builders, do you want to avoid dissatisfied clients with regard to sunken and settled concrete? Here’s how.
Follow industry guidelines for compaction. Yes I know these are not enforced but they are a sure way to nearly eliminate all settling. It costs to do compaction according to industry standards, it costs to take the tests and document the results, however by doing this you insure the end user, the homeowner a superior product. Advertise it, let potential clients know you provide a service that virtually no one else does. Quality sells.
Do not pour concrete on unprepared top soil. All concrete should be poured over at least four inches of compacted gravel. Concrete is porous, water moves through it fairly quickly, if all it has is soil to drain into, and that soil is clay (which is expansive) the slabs will heave with the moisture and crack. Compacted gravel allows water to drain safely away.
Don’t saw cut control joints, form them into the concrete. We have found virtually all control joints which are saw cut, are not of sufficient depth to work as intended. Conversely, we have found formed control joints nearly always perform as intended.
Use rebar. In most cases concrete will crack, whether due to shrinkage, thermal (expansive soils) or dynamic loads. Rebar allows concrete to crack without causing the slab to dislocate vertically or horizontally. A cracked slab with rebar can always be Slabjacked, without rebar it is much trickier to align the slabs perfectly.
Pin horizontal slabs to vertical walls with 5/8″ rebar when possible. Driveways to garage foundations. Patios to foundation walls. Garage floors to foundation walls. Yes it is more work, but when coupled with proper compaction, provides an added element of stability for the slabs.
Provide a foundation or at a minimum, Sonotubes, under all entries which are more than a simple 4″ to 6″slab. Blueprints rarely specify the type of entry, rather this is dictated by slop of the land and personal preference, as a result the architect does not draw a foundation for this section of the house. We recommend all concrete entries have a foundation or at a minimum, Sonotubes of ample size, tied into the entry with rebar to support the weight anticipated.
All step up entries, all entries with columns, or those that act as support for any superstructure need to be extremely stable, in addition to the above we also recommend pinning with 5/8″ rebar every three feet to the foundation wall.
Backfill all slabs which will be in excess of 8″. A small entry of six by seven with two steps, if poured without backfill will weigh in excess of five tons and requires over three cubic yards of concrete. Poorly compacted fill simply cannot support this load and will settle until sufficient bearing loads are reached. This may be one inch, it may be a foot.
Don’t make the addition of gutters and down spouts an option, install them on every house you build. Plan for the elimination of water away from foundations walls at least five feet and slope soils well away from foundations, this will not only keep any basements dry but will greatly reduce settling concrete slabs.
Finally, if you are dealing with settling concrete on a job, call the concrete raising professionals 1-855-752-2522 – 1-855-752-2522
Superior technology, superior polymers, superior training, produces superior results.
When we are called out to bid a job, the damage, as they say, is already done. In this post we will be discussing the cause of most settling and what you can do to insure your slabs remain stable after we leave.
There are two primary issues that cause concrete to settle and they are often related; soil compaction and excess water. If you have settled concrete you likely have one or both of these problems, so, what to do?
Let’s discuss the first issue, compaction. After the home is built it is nearly impossible to effect the deeper layers of the earth around your home so unfortunately, if your builder failed to compact, which is the rule not the exception, time will have to take its toll. Typically the major settling will take place in the first two or three years and by year seven or so, you’re generally finished with the worst of it.
The second issue, dealing with excess water, can be frustrating, especially if no thought was put into dealing with the inevitable rain and snow melt when the home was being built. So, what can be done after the fact?
1) Install gutters and down spouts. Down spouts should be directed at least five feet away from foundation walls and from walks and other concrete slabs. Of all the slabs we raise, the most common is the one right in front of the entry. Why? A down spout, or roof design is nearly always dumping water at that point.
2) Do not plant bushes or sod near foundation walls or sidewalk slabs. A good rule of thumb is to allow five feet between the foundations and plantings and two feet between walks and plantings. Plantings too close to walks or along foundation walls, cause root issues, erosion issues, and compaction issues. A Slabjackers paradise! Something to remember, most trees and bushes have a root system that is 50% larger than the width of the canopy. That nice looking Japanese Maple that is nearly touching your eve has roots extending along your foundation and under your sidewalk. Water follows the roots and before long you have voids that further take top soils away and settling is well on its way. For an interesting example of what roots can do to a driveway, go to our web site www.SlabjackGeotechnical.com and in the before and after pictures look at the driveway photo. (We had to raise three additional slabs to match the one that was raised)
3) Maintain fill along slabs, fill in any erosion you see prior to settling occurring and if all else fails, call us when the settling starts, before cracks develop, to raise and stabilize your slabs.
4) Give your sod and plantings the absolute minimum amount of water to keep them healthy. Turn your sprinklers down until the sod begins to suffer then turn it up slightly. Too much water cause funguses, such as necrotic ring spot and mushrooms to grow and some soils such as clay, allow concrete slabs to settle because water saturates, then drains very slowly through them. A good example of this is a job we did in the Wenatchee area; a sidewalk was settling, inspection showed fully saturated clay down to a depth of over six feet! We could literally stick a probe two feet into the ground with one hand! We advised the home owner to turn off her water for a week and to reduce the timer to ten minutes on that zone verses the forty minutes it was programmed for. Too often what sod needs is nitrogen and it keeps getting more water because “it isn’t green enough”
The key to stable concrete is a stable base, you can’t do much about compaction after the fact but you can reduce waters role in the equation. Plant well away from foundation walls and walks, reduce sprinkler timers to only what is needed. If water is pooling you may have clay soils and need to further reduce watering. If flooding occurs or you notice soils have washed out along slabs, replace the fill as soon as possible. Finally if you notice settling call the concrete raising and leveling professionals 1-855-752-2522, the answer to settled and sunken concrete all across Eastern and Central Washington.
Superior technology, Superior polymers, Superior results.