Tom gets a call because the concrete at a warehouse is heaving. Check out what he finds underneath the concrete!
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ACI (American Concrete Institute) says that you “place” concrete. Just saying.
Curious? How did you concluded the mill slag was a part of or big part of the perceived problem?
And did you consider that the heaved area may have been harder ground and the adjacent areas had more fill and settled slightly?
I would think that with this entire building you'll have area after area doing this. It may be an idea to directionaliy drill under it to make a drainage network under the whole site to drain it…. I suspect the ground is heaving under all of it like permafrost. You may have to go to the trouble of building a subterrainian dam upstream of the building to divert or detain water that may make its way under the building. To top it off, as prior suggested, you will have to pump water out from under the building so a sump with a pump would be required. Be careful with this idea as well because you might be disturbing contaminated fill – who knows what might be in the mill slag that is exposed – mercury & arsenic come to mind, get the slag analysed for a work safety measure as to any toxic component in it, otherwise you may reap the whirlwind Ohio SNR style… take care. The other issue to consider is equivalent foundation performance, where what you put in must match the performance of the existing foundation, otherwise it will keep cracking. I'm surprised by how little reo is used.. I wouid have thought two layers of 4" x 4" 5/16 mesh would be required with a lower layer of 1/2" bar at 2' spacings would be used for this slab – as it is trafficked.. but then that may not 'performance match' the existing slab that I suspect you're doing.
Expandable soils? Yep, we have reactive clay soils here…. but… try this one – Tidal Soils & foundations. I worked on a building in Homebush Bay in Sydney, New South Wales Terra Australis. I was told the slab heaved up & down 1' twice a day with the tides… the building frame didn't as it was on 60' piles with a perimeter beam. Glad I found this out as the freezer I was working on was on that slab. All connections to it had to be flexible.
At 28:26 – I think you actually mean the silts build up at the base of hills over tens of thousands of years?
Great content, but the music is awful.
Couple of questions, if they had run rebar would it have lifted that much. I did not see any. If it is caused by moisture, why is it only happening in the middle sections not at the outer perimeter where there would be much more moisture. Was a stem wall installed around the perimeter? If you are getting groundwater a couple feet down, is that not your problem? Pouring over a high moisture/water saturated sub can never be good. It did last a long time under those conditions. Last thing, I have seen pads poured on the ground and were considered floating pads, no issues. Seems that should work granted you provide expansion joints. Thanks for the information.
You said the water I table was high. Would it have helped the floor to run a drain around the whole building? Say four feet deep just to get rid of the water issue? Thanks later
This channel puts victory concrete to shame… no slow people handicap people drug people or thieves
Just professionals
Real nice job. I worked on a state road repair several years ago where we did a road cut for traffic signal conduit installation. The subsurface was at least 8 inches over the original 10 inch reinforced concrete roadway. After installing the conduit, before we re-poured the concrete reinforced section, we were told to mate the new and old concrete with an application of Sikafex Sikadur to the cut face of existing concrete roadway surface. We applied it with a brush similar to that used to clean a concrete chute on a mixer. The next day that stuff was so hard, but resilient, that it could not be cracked off the brush, no matter how hard we beat it on a rock.
Question for you. If someone came to you and needed broken up concrete thatyou removed from a job so that person could fill in a road to harden up the soil, would you give it to them?
The other issue you need to be aware of is if increased moisture levels caused the soil to raise…what will happen if you enter a very dry period where the moisture will decrease and the underlying soils will shrink. I have personally dealt with numerous events where floors heaved because of a broken water line in expansive soils. To correct that the concrete that is replaced must be capable of fully supporting the floor with zero support underneath (hollow) making it essentially a bridge…something to consider.
No rebar
Hey Tom, first time viewer of your channel here. First, great episode and wonderful explinations. Thank you! We ran into a similar issue in Lubbock, Texas back in 2009. Slag was used as a base media, and we found that every time it rained our warehouse would heave. Our company was a distributor of water chemistry for industrial treatment so 275 gallon totes would go in and out all day on forktrucks. We would avoid traveling over the effected area when it did heave, as best we could. That said, we did not tear out. Instead (since the building was at the base of a hill and water was pooling in a low area around the building) we built a 3' deep french drain around 3/4 of the building. Mainly around the areas were no traffic would be. Almost instantly the slag stopped heaving as we diverted any water away from the foundation and out toward the street for runoff. This solved our issue, and 14 years later we're still doing great! Might be something worth suggesting. We also placed a few layers of poly in the bottom of the trench and up the wall toward the building, then covered it, to prevent any passthrough leeching. It's not cheap, but it's cheaper than pouring 3000 sq.ft. of concrete again. Water, it's a huge pain in the butt.
Great episode! I'll be back for sure!
Better call the dirt doctor. A slagectomy might be the whole cure that slab needs, or it might just be waste of concrete.
Why wouldnt you have a slip joint between the old and new….if you pin them together will the old expand and raise the new?…fill with inert sand on top of a membrane
Killing it my guy
So u just use 8s in it ass the way up (8s are 3/4 minus limestone w very minimal finer stuff, just enough to compact)
Ohh shit tell joe he better get a mini excavator for that expandable soil
in California this would be all done by Mexicans
I enjoyed the video, nice work. Suggestion, hard rock during the time-lapse is hard on the ears. Neutral music works much better.
I spent a career in commercial/industrial construction supervision, & my compliments on this video!… very clear presentation from the guy doing the work!
I’ve forwarded this on to construction colleagues, recommending both the video & the many astute comments to it.
While you might have some expansive clays in there, the culprit is likely the slag itself. When moisture moves into areas of slag backfill it causes it to corrode and the corrosion causes significant expansion.
So without watching video. I'd say clay , peat or under ground water causing the dirt to walk . I also didnt notice any expansion joints.
I spent 40 years doing this sort of work and 10 years of forced retirement, my customers were the smartest people in the world. These guys are good. The mag and the trowel combo is great. Yes and I knew Colorado. I think it's funny most of these guys want to retire but when you can't go back on the job it sucks.
Caused by lime in steel plant slightly it dosenf hpen with blast furnace slag
They could do with a good drainage system at the side of that building where the hill is, might remedy this for the future