The siren song of this forum. Lol
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If your driveway is anything like mine, itās cracked.
I have an asphalt drivewayā¦heheheheā¦but my neighbor has a 2 car wide laneway that is 40ā longā¦not a crack or delam or spalling on it in 15 yearsā¦and like I said I live in Ottawa Canada where we have frost down over 4ā in the winterā¦
But like any good Canadian driveway Iām sure he has a relief cut every 8 ft. And rebar for days.
Itās not a matter if concrete will crack itās just a matter of when.
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I always tell people that same thing with a slight modification. The only question is when and where it will crack. You canāt control whenā¦ you have some control over where it will crack.
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Yeah youāre right. Hopefully we wont keep our MR1 outside in the weather. Concrete cracks due to expansion and contractions. Going from 0 degrees to over 100F takes its toll. And the fact that no one will be driving an F250 over it everyday.
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I would of thought that coat hanger wire would be too smooth for miniature rebar ā¦ rebar usually has ridges to grip in the concrete. This is not a big piece of concrete anyways, so it all overkill lol.
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I have used coat hangers in hot tub slabsā¦shed basesā¦exterior concrete countersā¦
Coat hangers are not straightā¦they are looped and bentā¦
Rebar has ridges as it put under more lineal stress
I use insulation hangers for my counter tops. Never had a broken slab yet.
At the risk of criticism for over thinking or over the topā¦ I got my hands on a Schmidt Hammer (Swiss Hammer or Rebound Hammer - whatever jargon suits you) and tested my test pours. Day 8 after pour:
1st pour (No sugar added)
4500 psi 4700 psi (Edit: Chart interpolation error)
2nd pour (Sugar added to water)
4650 psi 5100 psi (Edit: Chart interpolation error)
10 readings taken from each sample on the under side (smoothest portion). Due to the lower readings on the 1st sample, I stoned the top and did an additional 10 readings with the same results.
Again, this is Q-Max mix which is advertised to have 5000 psi at 7days and 6500 psi at 28 days.
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Thatās some awesome information. I am going to use the sugar in the Quick crete high strength mix. Never knew about all the options available? I will sure be glad to get those 10 bags out of my shop. Still waiting patiently. Maybe this weekā¦
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Out of curiosity, where were you buying the Q-Max? Seems like good stuff, but doesnāt seem like any of the main local stores carry it where Iām at
Local Home Depot carries it.
Just curious. In the long term and concrete being corrosive, how long will the steel parts last that are embedded in it?
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Probably longer than the machine. You know 99.9% of concrete slabs are full of steel that isnāt even painted.
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I have been lurking in this thread and have considered commenting in the past but resisted. Sorry about the long post. I hope some find it helpful.
On a previous project I was asked to inspect a group of concrete and masonry buildings in the Pacific Isles(fancy way to say Hawaii 
) that were experiencing considerable deterioration. That being the case I spent a significant amount of time studying the cause and effects of corrosion of concrete and masonry structures.
At the end of the study I produced a long and detailed report of my findings. However, I am going to try to keep this shortā¦ nobody needs a book about corrosion on here.
Cured concrete does not cause corrosion in steelā¦ it actually does the opposite.
Cured concrete is a highly alkaline material, typically having a pH above 12.5. This environment is created by high levels of calcium hydroxide in the concrete and helps to protect embedded steel from corrosion. Essentially, a protective film is created around the embedded reinforcing steel. Since steel corrosion needs a neutral or acidic environment to flourish, the steel is effectively protected from corrosion by being encased in concrete.
There are many internal and external forces that can lead to deterioration and premature failure of concrete construction. The most common causes are chlorides introduced by water infiltration, carbonation, corrosion of reinforcing steel, poor construction practices and inferior construction materials.
Corrosion of embedded reinforcing steel is both a cause and a symptom of deterioration in concrete construction. Corrosion is not however caused by its interface with the concrete as pointed out above. There are several different mechanisms that can cause steel corrosion. In order for steel corrosion to occur, three ingredients must be present: moisture, oxygen and an electrolyte.
Okay, I said I wasnāt going to write a book, so I deleted half of what I wrote. I find it sufficient to say that concrete will not cause corrosion of steel. Corroding steel can cause significant deterioration of concrete if the ingredients listed above are present, we have all seen evidence of that.
For these reasons I would advise against adding any additional type of metal reinforcing above what is provided by the manufacturer in your MR1 concrete pour.
My ultimate recommendation would be to follow the manufactures recommendations to a T ā¦do exactly what the directions say.
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Thanks for the explanation! There are already steel ribs and other parts in the āslabā but they are totally imbedded in the slab. Are you talking about metal that is exposed to the outside?
Cheers,
MIke
Iām saying donāt add anything extra, just follow the directions. I made an edit to the comment above to make it clearer. Thanks for pointing that out.
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So did you ask to do all your investigating studyās on site?
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Yes, we did allot of testing onsite. And yes, I did take some time to enjoy my surroundings! I talked one of the local contractors I hired to assist in the destructive testing into giving me body surfing lessons before and after work. It was a fun project. Actually got more work in Hawaii because of the initial report. I have been lucky to do work and travel to 6 of the 8 islands.
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