Ideas from Ed: Crack attack! (December 2019)

Ed is a do-it-yourselfer who is happy to share some of his ideas and experiences in this monthly column.

This month:  Crack attack!

One thing is for sure.  If you have concrete anywhere, it will crack sooner or later.  It may be from frost heave, differential settlement, poor construction techniques, or one of many other reasons.  When concrete is placed (BTW, that’s the proper term, instead of “poured”), hopefully there will be “control joints” either made during the installation, or cut into the concrete afterward.  What those (hopefully) do is to make weak points in the concrete, so that when it cracks, it will do so where you want it to, rather than where it wants to.  On smaller jobs, like a sidewalk, the usual control joint is at the union between blocks.  Walkways have an inherent tendency to crack because they are placed onto the ground surface, and have no “footing” down to the below-frostline depth.

To make a long story short, this month’s article shows you how I deal with small cracks that occur.  One way, of course, is to mix up some mortar and water, and to trowel it into the crack.  Since it will “harden” when set, it is likely to further crack, as did the original concrete at that spot.  A better option might be to use something flexible, like a good silicone caulk, and simply squeeze it into the joint.  At least small movements later on have a chance of keeping the repaired joint intact.

You can purchase gray colored caulk, or even supposedly concrete-colored caulking tubes made just for this purpose.  Some of the concrete repair tubes have a bit of “texture” to them to imitate concrete better than plain smooth caulk.  I’ve never found one that looks good enough to suit me, so I use the method shown below.

First, here’s the crack of the day.  It’s a small section of walkway, repaired many times over using mortar and even leftover grout from a tiling project.  (The tile grout is the reason the joint is “white”, and I’m not really dealing with that at this point.)

The first step is always to clean away any loose dirt and debris.  That probably goes without saying.  Then fill the joint with your favorite brand and type of caulk.  Something with silicone holds better than caulk that’s only latex-based.  As always, I am not endorsing any particular brand of product, but the picture shows what I used for this project.  You might note that this particular caulk goes on white but turns clear once it has cured.

You need to have some paper towels handy, because the next step is to smooth out the caulk, and I’ve yet to find anything better than my fingers.

Then, quickly, because some of today’s caulks set up very rapidly, sprinkle on a mortar mix, or better yet, plain old sand.  Be liberal. 

Then, use the flat of your hand to “tamp” the mortar/grit/sand into the caulk.

Wait until everything has set and you can brush away the excess, or forget about it and let the next rain clean off the excess.  It should look something like this when you’re through:

I think you’ll find the repaired joint looks better than using caulk alone, and the flexibility of the joint gives it a fighting chance to remain intact!

I hope all your projects go well.  Thanks for reading, and happy restoring!

Ed