Concrete failing around cut lines.

[penright]

My driveway is about 2 years old. It starting to break up around the cut lines.
What can I do to keep it from spreading?
Two examples, on on a corner the other in the middle.
BTW, the driveway is really long and wide.

 

[doctordirt]

Re: Concret failing around cut lines.

Cut lines are only half the job. Other half is to clean joint install backer rod and seal joint with SL1. It is a self leveling joint sealant.

 

[lakeroadster]

Re: Concret failing around cut lines.

After the fact... not much. Using angel hair fiber in the concrete mix helps to minimize these issues.

Did you seal the concrete?

Caulking the joints, as doctordirt stated, with a product like Sika-Flex will help keep water and foreign objects out of the cracks. And if water does get in, the sealant adds flex so that if the water freezes it's less likely to crack the concrete.

 

[machsnell]

Re: Concret failing around cut lines.

That's a shame. Good looking finish job on concrete and nicely cut joints.

Add backerrod and caulk as suggested. Don't use self level if it's on any slope. Regular sika is fine just use tape or be careful if you aren't experienced to have it come out well.

Maybe salt got inside from car runoff and found a weak spot or as mentioned water found a cavity and popped it. It's odd that it is literally crumbling though. You see concrete crack in slivers often on joints but not crumble. Would love to hear some other takes on cause.

Sent from my SM-G930V using Tapatalk

 

[EOC_Jason]

Not to derail, but which Silka is the non-self leveling? Home Depot had two kids in the caulk tubes (Self-Leveling Sealant and Crack Flex Sealant) and when I read the labels both were self leveling...

 

[Retroman]

I wonder how deep those saw joints are? engineers spec them at 25% of slab thickness may have been cut to deep. I have been in the concrete cutting business a long time normally see that in warehouse's with hard rubber tires on fork lifts.

 

[lakeroadster]

Not to derail, but which Silka is the non-self leveling? Home Depot had two kids in the caulk tubes (Self-Leveling Sealant and Crack Flex Sealant) and when I read the labels both were self leveling...

The ones listed as "non-sag"....

https://usa.sika.com/en/solutions_p...dential-home/products/02a024/02a024sa008.html

 

[TommyK]

Lay a straight edge across the joint and see if there is any evidence of curling. If the joint has curled it will chip/spall when a load goes across it.

Are there any expansion joints in the slab or just control joints?

Those types of failures can also be attributed to excessive water in the mix although I would expect them to present sooner than 2 years if that were the case.

 

[ard]

This is outside in a (very?) cold climate? Can freeze/thaw/freeze do this if water/ice gets trapped in these cuts?

 

[lakeroadster]

This is outside in a (very?) cold climate? Can freeze/thaw/freeze do this if water/ice gets trapped in these cuts?

Yes. That's the value of adding the Sikaflex.

Caulking the joints, as doctordirt stated, with a product like Sika-Flex will help keep water and foreign objects out of the cracks. And if water does get in, the sealant adds flex so that if the water freezes it's less likely to crack the concrete.

 

[Falcon67]

This is outside in a (very?) cold climate? Can freeze/thaw/freeze do this if water/ice gets trapped in these cuts?

He's in OK, similar to us in west TX - can go from sleet storm to shorts and shirt sleeves in 24 hours.

 

[ConCretin]

I'm with those who have suggested mechanical damage from wheels or other types of wear. The pics make the joints look very wide to me. I'm wondering about a very wet mix that had a lot of shrinkage and low strength making the edges susceptible to damage? The color of the concrete also suggests a wet mix to me but it could be many things. Obviously hard to tell from a photo.

Caulking the joints might help prevent future damage by providing a little support and protecting the edge. Use backer rod first and fill as high as you can. Sounds OCD I know but I like to tape the edges to keep them clean.

 

[penright]

Thanks guys.
Let me take more pictures and measurements since I know more what you are looking for. I have Church tonight, maybe I can get it before we leave.

Lay a straight edge across the joint and see if there is any evidence of curling. If the joint has curled it will chip/spall when a load goes across it.

So, if the joint runs North/South, lay the straight edge East/West. I will do it and report back.

Are there any expansion joints in the slab or just control joints?

Yes, I will get more info and report back. The drive is really long and wide.

Those types of failures can also be attributed to excessive water in the mix although I would expect them to present sooner than 2 years if that were the case.

I have lived in the house for a year and it was about a year old when we bought it. There are other stress, They are getting worse. It would not surprise me if it was a bad batch.

Did you seal the concrete?

I did not. I suspect it was not done.

Cut lines are only half the job. Other half is to clean joint install backer rod and seal joint with SL1. It is a self leveling joint sealant.

I need to do some searching. I guessing the backer rod is flexible enough to move, but keeps from using a bunch of seal joint. Any suggestions on installing it?
I also have my new drive back to the shop, I guess I need to do.

 

[ConCretin]

I need to do some searching. I guessing the backer rod is flexible enough to move, but keeps from using a bunch of seal joint. Any suggestions on installing it?

The purpose of backer rod is to create the proper caulk profile. Ideally the caulk has a concave shape on top and bottom. This maximizes the bond area on each side and creates a thinner center that can stretch easily. It comes in varying widths. Get one that fits snuggly and push it down about the distance that the joint is wide.

 

[lakeroadster]

The purpose of backer rod is to create the proper caulk profile. Ideally the caulk has a concave shape on top and bottom. This maximizes the bond area on each side and creates a thinner center that can stretch easily. It comes in varying widths. Get one that fits snuggly and push it down about the distance that the joint is wide.

Or use sand.... on tight joints it's mighty difficult to use backer rod.

Just be sure to maintain the thickness of the joint sealant that is recommended by the manufacturer.

 

[EOC_Jason]

Or use sand.... on tight joints it's mighty difficult to use backer rod.

Great tip! There's mounds of that stuff around here from the new home construction leftover from when they do the brick veneer... Landscapers just end up spreading it out over all the trash and bricks on the ground before putting a thin layer of dirt & sod...

 

[6768rogues]

In NY we have plenty of freezing weather. When I worked for the county, their specs always called for tooled joints in outdoor concrete, saw cuts were not acceptable. I took that advice with me and I have avoided what you have.
Those look like control joints, not expansion joints. We do not fill control joints.
If you get freezing weather, moisture and freezing might have done it. I would clean out the joints and coat them with sealer to seal up the raw cut edges. Tooling rather than sawing would have left a more protected surface.

 

[3504speed]

A pic of backer rod for the OP to see. I modified this electrical box extension to place the backer rod at my desired depth. Worked great and made the backer rod install go really fast.

https://www.garagejournal.com/forum/attachment.php?attachmentid=748825&stc=1&d=1521694045

 

[eddieK]

This is outside in a (very?) cold climate? Can freeze/thaw/freeze do this if water/ice gets trapped in these cuts?

my thoughts exactly

 

[penright]

Those look like control joints, not expansion joints. We do not fill control joints.

Thank you guys for the terminology. That is so important to communicate properly. That term make sense, it "controls" the cracks.

Yes, they are control joints. Does that mean I should not fill them?

The expansion joints look fine. Which makes sense about your comment of finishing the control joints, instead of cutting them.

I did not measure, I just step it off. Here is a picture while I describe the size. I guessing about 3ft per step.

From road to single garage door 96 feet.
Width about 15 feet.
Width in front of double garage door about 18 feet.
Distance from double garage door to curved part about 18 feet.
The drive going back to the shop is about year old and seem to be ok, but does not have the traffic the front has.
If I am guessing right there is about 180 feet of control cuts in the main drive.

I wonder why this drive is susceptible to tire marks. I just had a storm shelter installed in the double door garage. This picture was taken after backing trailers and the bobcat had rubber treads. So it looks worse than normal, but there is always marks. They wear off fast. I always assume it has to do with the approach to the double door garage. You have to make the swing just right depending on which side you are lining up for. My wife and I have it down now. I always suggest that people test before laying any drive down. The main drive was in we bought the house. The sub contractor that did the drive to the shop worked with me to get it right for the door in front of the red Grand Prix. There was a plan in case I put a fence across the front.
Just to be clear, the damage pictures was before the shelter installation.

 

[penright]

He's in OK, similar to us in west TX - can go from sleet storm to shorts and shirt sleeves in 24 hours.

This picture was taken 2 days after it was in the 70's

 

[penright]

Lay a straight edge across the joint and see if there is any evidence of curling. If the joint has curled it will chip/spall when a load goes across it.

Holding a straight edge on the high side. Looks like about 1/8" after 6"
Is that too much?

 

[lakeroadster]

In NY we have plenty of freezing weather. When I worked for the county, their specs always called for tooled joints in outdoor concrete, saw cuts were not acceptable. I took that advice with me and I have avoided what you have.

Tooling rather than sawing would have left a more protected surface.

I think there is a lot of wisdom in 6768rogues' advice. The curved profile of the tool makes for a better engineered contour and minimizes stress risers. It also creates a V-Shaped profile instead of a square sided groove. The V-Shape allows freezing water a better path of movement.

I think back to our previous concrete driveway. It had tooled control joints and tooled contraction joints. They held up well with minimal cracking along the edges.

However where there were cracks in the concrete, it broke apart just like the OP's photo's of the saw cut control joints.

I opened the cracks up with a diamond grinding wheel on an angle grinder and then applied Sikaflex.

 

[ConCretin]

I like tooled joints as well. The rounded edge is definitely less prone to spalling. The only problem with a tooled joint is that it is difficult to get the desired depth of 1/4 of slab thickness. You have to groove early in the placement with a deep groover so you can push all the aggregate aside and repeat several times If your finisher isn't prepared to do this and waits too long, you'll have a nice decorative groove but it won't be deep enough to dependably control cracks.

With regard to potential curling, it's hard to tell from the straightedge photo but I tend to doubt that is the problem. Curling most often occurs at slab edges when the top of the slab is 'dryer' then the bottom. It usually occurs on interior slabs particularly at the start of heating season. I've seen it with and without vapor barriers. It's a factor of differential moisture. In any case there isn't much you can do about it at this point.

If you are up for some dusty, back breaking work, you could profile the edges of your joints with a diamond grinder. There are many profiles available for chasing joints like yours. This would eliminate the sharp edge and might reduce future spalling.

Finally, I see no issue at all with caulking your control joints. It's always advisable to keep water out of concrete.

 

[EOC_Jason]

Funny thing... My driveway has tooled joints, I can see the cracks at the bottom of them so they did their job...

My neighbor has cut joints, and there's a spot on his driveway just like the photo above with a chunk broken out on one side.

 

[Falcon67]

Can't help to OP much - LOL on the snow pic because I ran the weed eater between ice storms here. The drag strip here is two continuous pours of 25' W 12" T x 900' L. They saw cut each lane at 20' and use backer rod and self leveling caulk. The lanes broke at almost 10' intervals anyway and chunks are missing around the saw cuts as in the OPs picture, some fair sized. Hasn't affected operations of the track and we've had Top Alcohol cars run on it, best past 1/8 run 3.87 @ 220. But up close, it looks like hell in places. I do not know of the batch specs, but last time we had Penhall come grind the track surface a 2 day job took a week because the rock in the pour is hard as hell.

 

[penright]

Funny thing... My driveway has tooled joints, I can see the cracks at the bottom of them so they did their job....

Just thought of another point for tooled joints.
My cut one have cracks also, so they are doing "that" job. But with cut joints the saw has to stop before the brick (curve of the blade) where the concrete si laid up against it. You see the crack leave the cut and then start sneaking around at that point.

I am not a concrete guy, although I did labor for one during my highschool summers, but if you are tooling it, I would think you could go all the way to the brick.
How much do you think it would add to a concrete job if they tooled the joint instead of cut?

My neighbor has cut joints, and there's a spot on his driveway just like the photo above with a chunk broken out on one side.

You know, thinking out loud, the garage floor has them too, I know they are not water freezing related.
I am thinking about the square point. As the tire moves onto it, there is a lot of pressure on that edge. But if you radius it back, then the tire doesn't have full contact on the surface till it reaches farther back, there is more meat between that spot and the edge.

If you are up for some dusty, back breaking work, you could profile the edges of your joints with a diamond grinder. There are many profiles available for chasing joints like yours. This would eliminate the sharp edge and might reduce future spalling.

Did some googling, must not be using the right terms. I keep getting granite top or surface grinders. Do you have any examples that would fit DYI grinders?

Finally, I see no issue at all with caulking your control joints. It's always advisable to keep water out of concrete.

Thanks.

 

[EOC_Jason]

I am thinking about the square point. As the tire moves onto it, there is a lot of pressure on that edge. But if you radius it back, then the tire doesn't have full contact on the surface till it reaches farther back, there is more meat between that spot and the edge.

Well I think the issue is the aggregate under the surface. With a tooled joint you are pushing that out of the way and get a nice finished surface to cure.

With a cut joint it's just cutting through anything and everything, so if there were some clumps of aggregate just under the surface by cutting through it exposes a weak point to start fracturing off?

If it was me, I would grind some so it wasn't a perfect 90, then fill with silka as per mfg recommendations...

 

[6768rogues]

I don’t see any reason that you cannot fill them. Put a couple of saturating coats of penetrating sealer on, let it dry, and fill them. When we leave them unfilled, we are leaving tooled joints unfilled. County specs forbade cut joints outdoors, but allowed them indoors in heated spaces.
By the way, nice place, Penright.

 

[ConCretin]

Did some googling, must not be using the right terms. I keep getting granite top or surface grinders. Do you have any examples that would fit DYI grinders

I figured Amazon would be an easy place to find so I did a search for 'crack chaser' to find an example of what I had in mind. This blade would chamfer the edges and remove the sharp edge.

https://www.amazon.com/dp/B003HLNW86/?tag=atomicindus08-20

As I mentioned earlier, your joints look quite wide so you'd need to get a blade that's wide enough.

 

[penright]

'crack chaser'

'Crack chaser' That was the magic word.

As I mentioned earlier, your joints look quite wide so you'd need to get a blade that's wide enough.

Looks like a 1/4" (.250) I found some that was 3/8" (.375). Does that seem right?

How do you hand ones that are chipped. Just let the silka flow out?

I am starting to wonder if I need a professional? I wonder what they should charge? What questions should I ask to see if they are going to do it right?

 

[mineallmine]

You can let the silks flow out and fill the broken sections. It will just take a little longer to fully cure .Watch to see that it levels out nice. I had to go back over a section or two as they settled a little more than I wanted. Also be careful not to put too much as it won't look as nice and clean. Just go slow. It's actually pretty easy. My cuts were about as wide as yours as well.

 

[ConCretin]

Looks like a 1/4" (.250) I found some that was 3/8" (.375). Does that seem right?

How do you hand ones that are chipped. Just let the silka flow out?

I am starting to wonder if I need a professional? I wonder what they should charge? What questions should I ask to see if they are going to do it right?

It's hard to say which blade you'll need - but wider is probably better. You want one that is wide enough to bevel the edge without disappearing into the cut.

We use a grinder similar to this one. It connects to a vac to collect the dust and has a plate that maintains a constant cutting depth. A bit pricey but maybe you can find a less expensive model.

https://www.amazon.com/gp/product/B0000VUN7E/?tag=atomicindus08-20

With regard to the broken edges, I'd take a shot at repairing them. Clean the areas to be repaired. Find a smooth material that will fit into the slot to act as a form. I'd suggest a bonding agent such as Armitec110 because it has a long working time. Finally apply a good quality patching mortar. Grind the repair the same way you do the rest of the joints and install caulking.

It's quite a project but its not all that complicated. You could probably do it yourself with a high degree of success. I'm not sure what kind of pros you have in your area but this kind of work is a bit specialized and can be pricey. You are probably looking for someone listed under concrete repair and restoration. Good luck.

 

[IowaDon]

While the points regarding tooled joints are valid, every paved concrete road in this country has cut joints. So do most driveways. They usually work fine. Yours shouldn't be failing at two years.

Chances are whoever poured your drive sprayed water on it to either make it easier to finish, or buy time because they were "losing" it. Unfortunately, this is a very common occurrence, and it is the most damaging thing you can do to concrete. It weakens the top more than salt, or ice, or anything else.

If I were you, I would remove the rubble, clean the joints, and seal them with a good sealant. Then I would keep an eye on it for awhile. I wouldn't do much more at this point, because if the top is in fact ruined by excess water, putting a lot of effort into it now will prove to be a waste of time and money.