Repairing cracks

[juddspaintballs]

I am building a house with a radiant slab for the first floor. We plan on dying the concrete with Delta Dye black and sealing with TS210. There is one large crack from front to back that not only has separated a good bit, there are bits chipping off in some areas and one side seems to be lower than the other. I don't know why this is happening since it is in an area poured all by one truck and the lower portion sits on top of concrete blocks about 2' away while the higher area isn't supported more than the normal compacted shale used in the rest of the inside of the foundation. There's 2" foam under all of the concrete. It doesn't matter. It is cracked and needs repaired before dying the concrete. There are a few other cracks in the concrete despite relief cuts, but all of those are tight and could just be sealed shut with some sort of caulk.

What's the best repair to use for the big crack and what's the best repair to use on the smaller cracks? I assume I'm going to need to grind the big crack open to fill with some type of cement and use something from a tube on the smaller cracks. Advise, please!

 

[kaymccampbell]

I like Sika products. Sika-Dur Crack Fix is my go to. I sprinkle kiln dried sand down the crack, then dose it with Sika. If I care about a color match, then I'll sprinkle Portland over the the top of things.

 

[juddspaintballs]

Thank you. Does it take dye at all?

 

[ConCretin]

The fact that the crack has separated and displaced vertically raises concerns that it's not done moving. Unlike shrinkage cracks, which usually occur soon after placement and don't move much after, your crack sounds like it resulted from inadequate support from below. I'd keep a close eye on it before investing a lot more time and money.

With that said, I've had great luck with Legacy's Xtreme set-100. You can mix it in small quantities, It pours like water and penetrates deep into the crack providing a structural repair. You'll want to run a crack chaser bit along the top to open it up a bit and use dry silica sand as a filler to keep the liquid from running out the bottom. I fill the crack with liquid to prime the concrete, fill it with sand and then thoroughly saturate of the sand with more liquid. A squirt bottle works great for the liquid and the sand as it lays in a nice even fill with a lot of control. The repair ends up proud of the surface but you can easily sand everything perfectly smooth after it sets.

I doubt any repair material is going to take the stain the same as concrete but you may be able to match the color. The Xtreme Set is available in a number of colors and you could use a colored silica sand. With some trial and error, you might come pretty close to a color match.

Let us know how it goes and don't forget the pics.

 

[juddspaintballs]

I never heard of a crack chaser, but now I'll be buying one. I was just going to use a diamond concrete grinding disc that I already have. The legacy Xtreme set-100 comes in black. I'm not expecting an exact color match, but the fact that it can be something close to the concrete is nice. I have no clue how much I should buy. 32 oz seems like enough.

Do I need to do anything to the small shrinkage cracks before Delta Dye and TS210 sealer?

 

[juddspaintballs]

I ordered the 32oz kit of Xtreme Set-100 in black and the pack of six bottles. I'll pick up some sand before it arrives and air dry it.

 

[ConCretin]

Do I need to do anything to the small shrinkage cracks before Delta Dye and TS210 sealer?

There is no need to repair the cracks from a structural standpoint. It just depends on if the crack or a repair looks better. If you have some slab that's won't be visible or isn't in a finished area, I'd do a few sample and trials runs before you tackle the main area. You can see which looks better and decide.

 

[juddspaintballs]

I have one big slab for the first floor. The first 24' are garage and the rest is the first floor of the house. It's all being dyed and sealed the same way and the only thing underneath anything is under the kitchen cabinets and under the stairs. Consequently, there are zero cracks in either of those places and the big crack is right between the entry door from the garage and the bottom of the stairs. There are a few hairline cracks in the garage despite relief cuts and a couple across the main living area. If the TS210 will seal them, I don't intend on putting anything in them to repair them. If they need filled to be sealed, then I will.

 

[juddspaintballs]

I received my Xtreme Set 100 yesterday (I was at work). When I got home today (Thanksgiving), I opened the package to find out that @LegacyIndustrial did not ship the six squeeze bottles I ordered for applying it. I had intended on repairing the cracks tomorrow and dying over the weekend. With my work schedule, this is going to set me back another week. I can't get drywall in until this is done. Bummer.