# Filling in a void with concrete



## head-first (Oct 28, 2010)

This summer I rearranged all of the brick around the front landscaping. There were two adjacent corners, and with my new design, I just loped the corners off and made a 45-degree angle across instead. In doing so, I now have a void that needs to be filled in. 

In the first pic, I am looking at the front of it. 






In the second pic, I am facing at the side of it.





What I would like to do is get this filled in soon. I was thinking of having someone do it, but it seems like something I could do myself. I am borrowing a B&D masonry book from the library, but still have questions:

Would I only need to use a board to separate between the brick wall and the void, meaning is it OK to allow the newly poured concrete to make direct contact with the older concrete?

The driveway is flat, but that sidewalk section has a grade to it, about 10 degrees. Is there a trick to filling in concrete at a grade? It seems like it would be thick enough to keep it's shape without drooping due to gravity, but I really have no idea.

Is there a good method to match a concrete mix with the preexisting concrete of my driveway?

Is it a good idea to add pebbles and sand to the ground first (to prevent erosion)?

So far I am looking at using this:
QUIKRETE® - Crack-Resistant Concrete Mix
Any good?


Thanks in advance for all input.


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## itsreallyconc (Oct 30, 2010)

looks like water will collect there if the slope of the sidewalk's any indication,,, couple bags of conc mix from the apron store & you'll be fine,,, expansion jnt would be a plus for the patch perimeter & score a joint across the shortest dimension to control the cracking.


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## head-first (Oct 30, 2010)

itsreallyconc said:


> looks like water will collect there if the slope of the sidewalk's any indication,,, couple bags of conc mix from the apron store & you'll be fine,,, expansion jnt would be a plus for the patch perimeter & score a joint across the shortest dimension to control the cracking.



Well, the idea is to get the water to follow the same path as does with what is already there around it. I added a new picture to show what I am talking about/thinking of doing...

The Yellow line represents the border of area that will be contiguous with the driveway and level. The red line represents the border of the area that extends from the walkway that has a grade to it. I am thinking the red area will be at the same grade as the walkway... leaving a joint in between the two grades as suggested.






So this expansive joint filler, I should incorporate that in between the block landscape wall and also in between the joint mentioned above? Or would I need joints around the entire perimeter, like in between the driveway and the new area?


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## head-first (Nov 1, 2010)

head-first said:


> Well, the idea is to get the water to follow the same path as does with what is already there around it. I added a new picture to show what I am talking about/thinking of doing...
> 
> The Yellow line represents the border of area that will be contiguous with the driveway and level. The red line represents the border of the area that extends from the walkway that has a grade to it. I am thinking the red area will be at the same grade as the walkway... leaving a joint in between the two grades as suggested.
> 
> ...



I moved some stuff around in my photo bucket account and saw that some pics disappeared from this thread. For some reason I cannot edit the thread starting post, but I could this post... this post has all the questions I need answered anyhow. 

If anyone can answer these questions quickly I'd appreciate it as I want to complete this project ASAP. Thanks.


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## itsreallyconc (Nov 2, 2010)

any apron store has isolation jnt mtl but, if it were mine, i'd use ' sill seal ' along the wall & the rest of the conc,,, after the conc's cured, pull the sill seal, insert backer rod, & seal w/joint sealant per directions on the tube


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## AlwaysOneMoreProject (Nov 6, 2010)

head-first said:


> Would I only need to use a board to separate between the brick wall and the void, meaning is it OK to allow the newly poured concrete to make direct contact with the older concrete?



It's a small job so I wouldn't use expansion joint between the new and old.  I would definitely edge those joints but I wouldn't space them.  



> The driveway is flat, but that sidewalk section has a grade to it, about 10 degrees. Is there a trick to filling in concrete at a grade?



Mix it normal and it'll hold.  If you use too much water, you're (drum roll, please) sunk.  

I would do the sections separately so that you can use the current slabs as screed guides without spearing anything.  The job will be easier to tackle, too.  



> Is there a good method to match a concrete mix with the preexisting concrete of my driveway?



The amount of money and time you'll invest in making that happen is immense.  Then, once you get it right, the difference in slab ages cause them to look different in a year anyway.  Your stuff will probably spall in a year because you're either going to over-work it or not keep it wet while it sets.  We all do it with these little repairs.  

Aesthetically, I would recommend that you cut the concrete so that instead of having that corner jutting into the void, that line echoes the line of the retaining wall.  If you're committed to that area being part of a walkway, pebble finish (float the concrete then sprinkle pebbles then trowel them into the surface) with a gravel that matches your retaining wall.  Otherwise, this improvement will always detract from your home's appearance.  




> Is it a good idea to add pebbles and sand to the ground first (to prevent erosion)?



If you were just laying a little slab, I'd say it's overkill.  However, since water is going to be flowing under from that wall, I would do gravel.  




> So far I am looking at using this:
> QUIKRETE® - Crack-Resistant Concrete Mix
> Any good?



I don't know.  My guess is that it has a little fiberglass in it to do what horse hair did for plaster.  It's probably not a bad idea.  The acute angles are going to be your weak spots and a little help wouldn't hurt.  

On the other hand, if you do the pebble finish or something else creative, you might turn a burdensome project into something fun.  I would enjoy it.  If that's the case, why not hand mix?


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## itsreallyconc (Nov 6, 2010)

*there's no such thing as crack-prroof concrete UNLESS its printed on the bags & put where homeowners can see them,,, anyone can print anything on bags but that doesn't make it fool-proof,,, IF anything is, we'll figger out a way to make better fools !

gravel = crushed stone ( preferably # 57 ) NOT bank run gravel OR graded aggregate base course.  *


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## mudmixer (Nov 6, 2010)

I would put the joint in the odd shaped are from the point protruding into the void area and run it so it is perpendicular to the little wall. This is where a crack would naturally occur. Other locations could lead to additional cracks even with a joint.

Fiber mesh is over-rated, but is does work for micro-cracking. The downside is the problems with under-mixing or over-mixing. - Not good for a DIYer to mix.

Dick


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## AlwaysOneMoreProject (Nov 6, 2010)

I read your other thread, too.  Something to consider, if you work for a living, is having a "professional" do the job.

There are many small timers out there that would love the chance to get their foot in the door with you.  Pick a one- or two-man outfit that's just started.  If they look right, show up on-time and bid the right price, you might have found yourself a contact that will be good for all your concrete work for decades to come.  

Obviously, this is advice that is far from your request, but if you work for a living, having such contacts frees you from this stuff to become a better employee.  

Finally, crushed stone.  That's smarter.


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## mudmixer (Nov 6, 2010)

Crushed stone in a water pathway is certainly pretty and "green" by some standards, but the stone allows the water to be adsorbed and possibly saturating the underlying soil.

The suggestion of a control joint was to give direction of the OP continued along with the original theme of filling the "void" with concrete.

Obviously this is a DIY project because of the size and only an idiot would use a contractor if he had the ability to either drag around bags of rock and place the barrier under them or mix a couple of bags and maintain the theme and not create foundation problems.

If the OP cannot do it, then he is welcome for find a small one man operation to do what he instructs them to do.


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## AlwaysOneMoreProject (Nov 6, 2010)

mudmixer said:


> Crushed stone in a water pathway is certainly pretty and "green" by some standards, but the stone allows the water to be adsorbed and possibly saturating the underlying soil.
> 
> The suggestion of a control joint was to give direction of the OP continued along with the original theme of filling the "void" with concrete.
> 
> ...



Relax, friend.  The "smarter" comment was to say that crushed stone, as recommended by itsreallyconc, is smarter than the gravel I suggested.  It wasn't in response to your expansion joint.

The advice about hiring a professional was in response to the fact that the guy was left begging for help in a thread that followed him saying he wouldn't hire a professional if he could help it... to a group made up of a number of professionals.


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## mudmixer (Nov 6, 2010)

AlwaysOneMoreProject -

I referred to a "control joint" and its location and never referred to being a "expansion joint", which is different.

itsreallyconcrete is well versed in concrete and accurately observed it was not a contractor job and a rock would be an alternate IF you did not want to accumulate water and debris in the "void" area.

I just suggested a joint location if the OP chose to pour concrete and recognizes the need to control cracks just as the other suggesions/options were pointed out.

Since there were not any clues to the location and climate, all that can done is to give suggestions. Rock will easily allow moisture to collect and be absorbed by the soil near the "void". My first "knee jerk" reaction was rock for a job of that size, but in a cold climate, the moisture allowed around and below the masonry wall could create a disaster and ruin the wall due to settlement or frost heaving.

Dick


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## itsreallyconc (Nov 7, 2010)

*i referred to what ?  this thread is so old i forget    IF it were my house, we'd have used bagg'd conc mix & be done in a couple hrs,,, i don't see any indication there would be collecting / settling wtr if the work's done correctly.

we use mainly #57 stone for sub-surface drainage - that's not the case here from what i recall  :beer:*


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## head-first (Nov 10, 2010)

OK, I finally have some time to get back to this. Thanks for all criticisms rolleyes and suggestions. 

As time is not in my favor, I did contact a small-repair concrete guy in town to get a quote, but he was too busy to connect with me when I was available. I figured that I can and will do it on my own anyway. As I mentioned, I took out a book about masonry from the library, which also has a DVD. After reading/viewing, I am confident that I can do it. 

Filling stone is the easiest option, and also my least favorite. Too much traffic and potential erosion.

I like the like the idea about cutting across and making the space trapezoidal. The sides will not be parallel with the mismatching dimensions of the side and it will have a somewhat odd shape, but unique is better than boring to me and I think it'll look very cool. It will up the price a little though, as renting a saw w/ blade for the job will be up around $50 (not including the extra concrete necessary for a larger void). I don't want to use my circular saw because that could throw off it's calibration with such rough cutting. I am going to check out some chisels. Somehow, I will make that cut, I'm just not sure how much I want to spend on that aspect.

I also really like the idea of creating an aggregate surface. That will be a plus for traction and appearance. This is also covered in the book I have and I think it'll be totally doable. And it does look fun.

Oh, and doing the sections one at a time seems like the way to go, especially after seeing how screeding is performed.

I will be back with my progress at some point.


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