# Concrete Stair Repair, Re-attach broken piece



## shawn2000 (Jul 22, 2013)

Hello, I am the owner of an Arts and Crafts home  built in 1908. My question today is with regard to a problem with a  small set of stairs. As you can see in the photos, there is a chunk of  the bottom stair that has been broken out. What I am looking for is  advice on how to attempt to re-attach this piece. I do not know wish to  have the stairs removed and re-formed, as it would require the removal  of the cobblestone retaining wall attached to it. 

As you can  see, I have the entire piece. And the piece will sit in place, although,  I cannot get it flush. Maybe I have to chip a little off of the back?






I can completely remove it.





A couple more for perspective.


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## nealtw (Jul 22, 2013)

two part epoxy comes to mind but some one that has used it would be better to advize you.


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## Chris (Jul 22, 2013)

I am also thinking a two parts epoxy, either that or a thinset type tile adhesive may work but the exopy will push it out less. You may need to chip so parts away to get it to fit back in but it came out of there so it should line back up.


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## shawn2000 (Jul 22, 2013)

I think I am going to have to remove some from the stair, as it will not fit back in perfectly, it sits slightly proud.   I believe the reason for the break is a crack in the sidewalk that runs up to the break (tree root I am sure). If I chip some away, the stair is probably the better place as it may not break so easily.


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## nealtw (Jul 22, 2013)

Or get your hands on a diamond grinder. And welcome to the site.


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## bud16415 (Jul 23, 2013)

The method I would use would be to cast a new corner in place after drilling and inserting a few pins into the old stuff from below and from the sides. 

If you want to replace the old piece and I can see why you might to match the ageing etc. I don&#8217;t think you will have much luck in just bonding it back in place. You also risk someone stepping on it and it breaking and them taking a spill. If you want to go the bonding method I believe you have to get the old material out and build a level / flat support surface for the piece to rest on then mortar that back in and or glue. With the slope surface I just see it getting loose again from water and freeze or the root and coming back off.


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## BridgeMan (Jul 28, 2013)

I've successfully repaired several similar broken concrete steps, although none as old as yours, and probably several hundred concrete bridge abutment and pier corners.  The trick is to first remove (by careful grinding) any high spots in the exposed base concrete.  It's best not to try to remove material from the underside of the broken-off piece, as you may fracture it.  A small masonry wheel will work just fine, and is a lot less expensive than a diamond grinder someone suggested.  Make sure all of the base concrete is clean, tight and sound--anything that sounds hollow when you drag a hammer over it has to be removed by judicious use of a geologist's pick.  You want to remove as little material as possible, otherwise you may wind up with an epoxy layer more than a half inch thick (not good).  Sand blasting is the best treatment for ensuring good bond of the epoxy, but a vigorous wire brushing can be just as effective for such a small area.  Give the area (both the base and chunk to be glued down) a good scrubbing with water and a stiff bristle brush, then either blow it dry with oil-free compressed air or just let it air dry.

Go to a masonry supply place, and pick up a small kit of low modulus, high viscosity epoxy (sometimes referred to as a gel, most of them are a light gray color when mixed).  Thoroughly mix the 2 components, and apply a thin layer on both surfaces to be bonded.  Press the piece into place, making sure some of the gel is squeezed out along the entire bonding surface--you don't want any voids that can collect water and freeze, causing the patch to break free in the winter.  Work a little powdered Portland cement and graphite dust into the visible bonding surfaces after you've scraped away all excess epoxy, which will make the epoxy blend in better with the color of the adjacent concrete once it cures.


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