# Concrete chunk fell off of entrance stairs



## curls00 (Jul 12, 2007)

Any suggestions on how to fix this? The crack started mid-winter (I guess from freeze/thaw cycles) and this week I noticed it was getting much looser, so I took my size 12 to it and kicked it right out.





























I've been thinking about getting a tube of the concrete patch stuff from a hardware store and using that like a glue (like liquid nails for concrete!). Would this work? The only problem is that the piece doesn't seem to fit back in 100% tightly... so will I have to resort to chiseling away part of the area that mates with the existing stairs to make it fit? Is that adviseable?

Also, about those two vertical cracks below the missing chunk -- what do I do about those to prevent future water infiltration??

Any other suggestions on how to fix this and make it look halfway decent? I don't want to spend hundreds calling in a mason to fix this since I have to put eavestroughs on the house this spring and do lots of other stuff that takes precedence over this... but of a mason is 100% necessary I guess I have no choice.

Thanks,
Eric


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## curls00 (Jul 12, 2007)

Anyone?


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## HandyPete (Mar 23, 2008)

Don't buy anything that remotely looks like glue! it ain't gonna work!

That piece is history. Get in touch with the folks at Mapei or Sitka. I prefer Mapei because they have an extensive line of concrete restoration systems. Their products are not cheap but, you get what you pay for.

Do I see wood inside the concrete? ouchhh! it has no business being there! The expansion or contraction of that wood is exactly why the concrete failed. Mapei's product may have enough elastomer's to give you a fighting chance (maybe)!

_ pete

"folks" means the Technical Rep. not a orange apron!


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## concretemasonry (Oct 10, 2006)

Pete -

Good eyes!

That concrete is not really old and weathered.

There is definitely wood buried in there and it could easily have expand to cause a shear failure if it had no where else to go.

The concrete looks very sound, judging by the rock that was split and not pulled out.

If you cannot get the wood out, leave a cushion or gap so it does not do the same thing again.


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## curls00 (Jul 12, 2007)

concretemasonry said:


> Pete -
> 
> Good eyes!
> 
> ...


So you're confirming Pete's recommendation NOT to go with the concrete patching/glueing, and to instead do a new form for that area and re-pour and feather? I think this is a job for a true mason/restoration guy since I've never poured concrete before... and being my main entrance, I don't want to screw it up to the tune of more $$ later. 

How, may I ask, would even a skilled mason, leave a gap on a vertical surface like that if they're re-pouring that section?


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## concretemasonry (Oct 10, 2006)

You need a gap to isolate the wood from the concrete, since it should have not been in there in the first place. I would also get rid of the loose piece of concrete below.

With the proper restoration methods, you should not need an open vertical joint, but a tooled false joint would hid or make any minoy cracks inconspicuous.


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## curls00 (Jul 12, 2007)

Well I emailed these pics to a mason in the area who specializes in concrete restoration, etc.

His quote was $1100-$1300. 

Includes seeing how far that wood goes, and removing it, laying rebar, pouring new concrete where needed, and refinishing the areas that were re-poured to match the existing stairs. Warrantied as well.

Sorry but I'll resort to bubble gum and duct tape before I pay over $1000 for a concrete repair job! That just sounds ludacris for what seems like a fairly straightforward job.


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## Maintenance 6 (Feb 26, 2008)

IMHO, What I see is a design problem. There are a lot of trapped corners with no place to absorb expansion. The wooden block was probably part of a form. I'd guess that it isn't trapped in the back and could expand if it had to, toward the rear. Even if you got the wood out, my guess is that the concrete would crack from expansion pressure. The wood happened to create the weak point in the assembly. In fact, the wood probably kept it from shattering even worse. I'd drill the concrete and epoxy some stainless pins in place and then form and patch it with a repair mortar. After that, I'd try to somehow saw cut a control joint at the end of the step and create a caulk joint to absorb expansion/contraction pressures.


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## curls00 (Jul 12, 2007)

Maintenance 6 said:


> IMHO, What I see is a design problem. There are a lot of trapped corners with no place to absorb expansion. The wooden block was probably part of a form. I'd guess that it isn't trapped in the back and could expand if it had to, toward the rear. Even if you got the wood out, my guess is that the concrete would crack from expansion pressure. The wood happened to create the weak point in the assembly. In fact, the wood probably kept it from shattering even worse. I'd drill the concrete and epoxy some stainless pins in place and then form and patch it with a repair mortar. After that, I'd try to somehow saw cut a control joint at the end of the step and create a caulk joint to absorb expansion/contraction pressures.


By "trapped corners" are you talking about areas where all 3 axis meet to form an inner corner (like at the base of the first step @ the side)?

I was reading a few articles online today about how to repair something like this and most said to use a hammer drill and get a piece of rebar in there... you say stainless though, I assume so it won't rust away. Then from there either pour a new section with good quality concrete or you're saying repair mortar? What is the difference?

By cutting a saw joint, would taking an angle grinder with a good masonry wheel to the very left and right edges of the first step, where it meets the vertical sides of the step, work? Make it as deep as safely possible, and then fill with caulk (in layers of course, if depth requires it) ??

Thanks a lot.


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## Maintenance 6 (Feb 26, 2008)

That is pretty much what I mean by trapped corners. The porch slab, front wall, step and riser all appear to have been a monolithic pour. There doesn't appear to be any place to absorb expansion/contraction. When all of this material started to expand/contract at different rates and in different directions, it placed stress in the assembly that showed up as a fracture at the weakest part. The old piece of wood happened to provide a relief point. I seriously doubt that the wood could expand enough to place sufficient pressure on the concrete to break it. In fact, wood trapped in concrete normally shrinks and gets loose, because the concrete absorbs the moisture out of it. I said stainless to prevent rust from expanding and blowing the patch apart. Steel re-bar with a good epoxy coating will likely work OK. I said "repair mortar", because repair mortars include a bonding agent that will adhere to the existing concrete. The pins will lock the repair to the existing concrete. I'd pin it because it is at the nose of the step and someone will be placing load at the extreme edge of the repair when they step on it. A thin blade on an angle grinder would probably work to create a control joint. Then seal the joint to keep water out of it.


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## Maintenance 6 (Feb 26, 2008)

Oh and don't caulk it in layers. See the other thread going on about caulking concrete. I posted a link about caulk joint design there.


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## curls00 (Jul 12, 2007)

So do you think re-pouring the area with the repair mortar (does that have large-ish stones in it like my current concrete?), will work... specifically, will making the overhanging lip (a few inches overhang) to match the existing contour of the step and riser, be strong enough?

How close to the edges of the existing concrete can I place a pin? Would placing one very close to the lip be adviseable, or could that cause more damage (cracking) while drilling, creating a much larger repair?

I'm off to go fishing this weekend but next week I will probably draw up a sketch with some detail behind it, if necessary... to show exactly what I'm talking about if you don't understand my non-technical speak. 

Thanks.
Eric


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## Maintenance 6 (Feb 26, 2008)

curls00 said:


> So do you think re-pouring the area with the repair mortar (does that have large-ish stones in it like my current concrete? NO, it shouldn't ), will work... specifically, will making the overhanging lip (a few inches overhang) to match the existing contour of the step and riser, be strong enough? That is what the pins are for, to carry the load when someone steps on the edge.
> 
> How close to the edges of the existing concrete can I place a pin? Would placing one very close to the lip be adviseable, or could that cause more damage (cracking) while drilling, creating a much larger repair? I wouldn't get less than 1-1/2-2 inches from the edge. Probably 3 pins for the step. One one the left of the wood and 2 on right. 3 inches of embedment and epoxied into the existing concrete. Avoid getting epoxy on the concrete surface. Set them so that the concrete patch engulfs them completely. You should remove the remaining fractured piece in the picture and pin that too. Don't put pins where you want to saw cut the control joint later. Build a form to match the exisitng contours of the step and then pour in the repair mortar. Work it down into all the voids very well. Trowel the top to match the finish as well as you can. You likely will not match the color. We fixed some broken steps like this several years ago and they are still in service with hundreds of people using them every day.
> 
> ...


Good luck with the fishing.


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## curls00 (Jul 12, 2007)

Well the fishing was very successful. 

Now back to my project. I am having a hard time finding any stainless pins/bolts longer than 3" total length. If I need to put the pin in 3" into the existing concrete, my only other option I can think of is to buy a 4' stainless threaded rod from Home Depot. It's 3/8" diameter though -- is this too small, or just right? From that I can make custom length pins.

I am not sure what product is considered "repair mortar" vs regular bagged concrete. browsing the orange aisles yesterday I came across the King 6000 PSI concrete sacks, which said that it is the strongest premixed availabel and is well suited for stairs, etc... much more-so than typical Sackrete used for fence posts. Will this King 6000 PSI stuff work well enough, or is there a specific product name you'd recommend for this application? You mentione drepair mortar is used because it has a bonding agent, but there are specific, inexpensive liquids sold everywhere they are basically a cement primer, so that new cement will adhere to the existing cement. Is the repair mortar better than using this, or is is basically the same thing, or will the repair mortar also require this solution?

And I assume any household 2-part epoxy would work to get the pins to hold? I have about 3/4 of a syringe of 5-minute epoxy left from a recent project, and was thinking of mixing up a bunch of it ant coating the pins (3" worth) and jamming them in the holes I'd be drilling. Sound about right?

Thanks again.


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## Maintenance 6 (Feb 26, 2008)

3/8 stainless should work. Threaded rod is ideal, plenty to grip fast to. You may want to add an extra pin or two to compensate for the small diameter. I would try to find an anchoring epoxy, rather than a general purpose material. Anchoring epoxies will hold better. 
http://www.simpsonanchors.com/Catalog/adhesives/set/index.html
I've seen anchoring epoxy at HD or Lowes near the masonry anchors.
Repair mortar will have some additives that bond to existing concrete better than patching materials. If you can find it, here is a link to what I would use. Or something similar
http://www.reedfirstsource.com/m7/documents/030100_10001146_01_FS_21509.pdf
http://www.lsepoxies.com/CR-60-Concrete-Repair-Mortar.html


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## curls00 (Jul 12, 2007)

I stopped by Rona (Canadian home improvement store) today and they carried a product by "bomix" (Eastern/Central Canadian company). Here is the one I was recommended: http://www.bomix.ca/produits.php?id=69&cat=rep&lang=en&p=20

It's a quick-setting, high-bond repair mortar. Sounds like what you linked to, but a different brand. My only concern is that it says maximum 3" thickness. I haven't looked at it thoroughly, but my repair, if I take out that bottom chunk (which I will do), will be about 12" high. But, the thickness from front to back wouldn't be much more than 3" though. Which measurement do I take? The picture for that product shows almost the exact area where my step broke... so I'm thinking it'll be OK.

I'll pick up some anchoring epoxy tomorrow, as well as the threaded rod.

Cheers,
Eric


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## curls00 (Jul 12, 2007)

Oh, here's the technical specs for the bomix stuff:

*Compressive strength ASTM C-109
*3 hours -- 6.3 MPa (913 psi)
1 day -- 12.2 MPa (1770 psi)
7 days -- 16.0 MPa (2320 psi)
_28 days -- 20.0 MPa (2900 psi)_


versus the specs for your Quikrete commercial grade:

*Compressive strength, ASTM C109 Modified*
3 hrs -- 2000 psi (13.8 MPa)
24 hrs -- 4000 psi (27.6 MPa)
_28 days -- 6000 psi (41.4 MPa)


_Is the BIG difference (basically 2x stronger) going to matter for this application? Or, with pins, will the stuff I am thinking about work just fine?


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## Maintenance 6 (Feb 26, 2008)

You're not going to drive a truck up and down the steps, so compressive strength isn't such a big deal. It looks like what you plan to use should work fine


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## kgphoto (Dec 2, 2007)

Cement-All will work very well there. High strength, quick set. 

Your patch will always show as a patch as the color will not match. The high priced mason was giving you a very good product if you read the specs. He was going to take out the wood and pour a whole step. It would have looked better than a patch. You get what you pay for.


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## curls00 (Jul 12, 2007)

If it ends up looking horrible, I was planning at some point to paint the steps with the textured concrete paint in a colour other than concrete grey.  Maybe that will be done sooner than later. Either way, that corner of the step is not noticeable from the street and 90% of the time, not even noticeable when walking up to the door since it's on an inside corner that people walk away from (partially).


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