Concrete Spalling Driveway + Other Damage. Cause & Best Fix?

[Stinger]

I bought this property last year. It has a large concrete driveway in front of the house (3200 sq ft), and back to the shop (280ft long, 6000 sq ft). Due to the amount of concrete and the insane cost of replacement, I'm wanting to protect it and prevent it from further damage. Everything was poured in 2004 (house) and 2008 (shop).

There are two problems with it currently (the second just showed up this week). The first is at the base of the driveway next to the curb/road. As far as I can tell, it started as spalling and has now basically turned to gravel. This area also becomes a drain during/after rain where water from the yard and under the slab appears to use this area as the path of least resistance to exit to the road (hence the vertical lines on the curb from water always running down it. I have to assume this issue is at least partly to blame for the spalling and destruction of the slab. If this is the case, what can be done to prevent the water from using this area as an exit? Would drilling a drain hole in the curb to prevent it from puddling behind the curb be reasonable? Is there something that can be done under the slab (after the damaged area is cut out) to build a "dam" of sorts to redirect water away from the base of the slab?


This area is obviously a lost cause in terms saving it and I assume the correct fix is to cut out the bad areas and pour new. The question is, how do I prevent this from happening again? I've seen repairs to areas like this before and it seems like a few years later the same problem is happing just outside of the repair area where the seemingly "good" concrete isn't so good after all. There are certainly very fine cracks around the gravel area (so fine that there is no gap in the crack, it's just visibly lighter colored).

The second issue just popped up after the recent extremely cold stretch. It was single digits here for about a week, we got a few inches of snow that didn't get cleared off the slab due to the extreme cold, and the city used rock salt on the surrounding roads. So once it warmed up and the snow melted, there was some exposure to salt that had been deposited by the vehicles driving from the salted roads to the garage. This new damage took a previously "good condition" slab with some fine cracks (again, no visible gap in crack, just lighter colored than the non-crack area), and caused spalling where the water/salt got into those fine cracks and caused it to expand. There are now areas that I can rub my shoe across and the concrete just turns to powder and a new 1" wide pit appears. These effected areas now appear to hold water (whole driveway is dry except for these fine cracks and spalled area), making me fear that the visible damage is nowhere near what's actually done (and that it's about to get really bad with some more freeze/thaw/salt cycles).

I rinsed the driveway to clear away any salt and then snapped a few pics of it while it was still wet that shows these damaged areas are raised now, and show all of the fine cracks I've mentioned. The other pics show the new damaged areas still being wet 2 days later, plus a better look at this new spalling.
Am I screwed here and this slab is a lost cause or is there a product or products that would allow me to fix/seal this new damage and prevent future water/salt/freeze damage? Thanks for your help.

 

[ybnormal]

Built in 2004 and it's already disintegrating? couple of questions:
1) you don't live near a heavily irrigated area, like a golf course, do you?
2) house elevation above the street and how far back?
3) it's hard to tell from the cropped pics, but how fast/hard and which direction does the water flow? steep driveway? level street?

 

[strutaeng]

Is that possibly from freeze-thaw? If you take a hammer and sound it, does it still sound good after removing the disintegrating part ? You take a chain and drag it across to listen for any delaminations. There's actually even a ASTM standard for that. Does any water pond anywhere?

You can do an overlay, but probably the best thing to do is bush-hammer to a specified depth. Most repair mortars have a minimum depth. And avoid a "feathered edge." Saw-cut a shoulder if you can't go to the next joint.

I had an excellent rep. from Sika that was very respected in the concrete repair industry. He always disliked anything that had that feathered edge phrase. He retired a few years ago, unfortunately. Learned a lot from the gentleman.

 

[Stinger]

No irrigation nearby. This is a residential area with farmland around the neighborhood but nobody irrigates around here.
House is 50ft off the street and elevation is probably 2.5-3ft. So it's sloped but not severely.
I'm near the top of a hill in the street, water flows towards the street and then to the left in the pics (towards the river rock that rain water also runs out of). It's not a massive slope and water flow is not flooding over the curb or anything crazy. The area where the most damage is present in the driveway is the lowest point.

 

[Stinger]

Is that possibly from freeze-thaw? If you take a hammer and sound it, does it still sound good after removing the disintegrating part ? You take a chain and drag it across to listen for any delaminations. There's actually even a ASTM standard for that. Does any water pond anywhere?

You can do an overlay, but probably the best thing to do is bush-hammer to a specified depth. Most repair mortars have a minimum depth. And avoid a "feathered edge." Saw-cut a shoulder if you can't go to the next joint.

I had an excellent rep. from Sika that was very respected in the concrete repair industry. He always disliked anything that had that feathered edge phrase. He retired a few years ago, unfortunately. Learned a lot from the gentleman

It's almost certainly from freeze-thaw IMO. The hairline cracks were already there and a week of single digit temps, a little snow, etc. seems to have done it in. Crazy it went 17 years without this happening and then all the sudden here it is though (this weather is not exactly abnormal for the area. We get single digit daytime temps at least a few days every year and it's sure to snow some of those times. Water does not pond anywhere.

I've not hit it with a hammer or did a chain drag. I'll have to do that later when I don't have people napping in the house.

I've not had good luck with cement based overlays in the past. Granted they weren't professionally done. I was assuming there might be an epoxy based coating available, maybe something that uses sand to help fill low spots in the spall areas?

 

[ybnormal]

No irrigation nearby. This is a residential area with farmland around the neighborhood but nobody irrigates around here.
House is 50ft off the street and elevation is probably 2.5-3ft. So it's sloped but not severely.
I'm near the top of a hill in the street, water flows towards the street and then to the left in the pics (towards the mailbox). It's not a massive slope and water flow is not flooding over the curb or anything crazy. The area where the most damage is present in the driveway is the lowest point.

yeah, your situation is a whole lot different from mine, which is why I asked. looking back at your pictures, I did notice one new thing.

the curb concrete seems normal while the driveway concrete is toast. that indicates to me 2 different contractors with 2 different mixes. I'm inclined to think the driveway contractor cheaped out. THAT, I would believe, having seen some of the things INSIDE my house, behind the walls. sure, the work lasts 20+ yrs but by then the contractor is loooooooong gone. (and the house has flipped a few owners)
“The bitterness of poor quality remains long after the sweetness of low price is forgotten.”

 

[Stinger]

Yes, I've noted that as well. I assume all of the fine cracks are do to "something" being wrong/cheap with the mix used but I don't know nearly enough about this stuff to know that for sure, or what the problem likely was. It does seem to be the root of the issue though. Fortunately my shop driveway doesn't have any of those fine cracks.

My house was actually the house the developer for the neighborhood built first and then lived in until he'd finished building all of the houses 4 years later and then he sold it. So it's a little more "premium" than the neighbors. Clearly that didn't apply to the driveway.

One additional detail is that there are a handful of other driveways in the neighborhood with the same "gravel" area near the curb. It's possible they were poured by the same contractor with the same shortcuts taken.

 

[strutaeng]

Ok, I missed the part where you said water flows across and and the deicing salt used by the city.

What probably happened is since that the lower point all of the bleed water wound up there as they were pouring and finishing the concrete. So the upper layer of the concrete got a lot of water and weakened it. I've seen that happened before.

 

[Stinger]

To get a "lay of the land" and a view of the entire driveway, here are two more pics. Should answer the questions about where the water flows, distance from house to road, etc. The google maps photo is from 2011 and shows there is no damage at that time as far as I can tell in the low-resolution pic. Certainly no "gravel" happening yet.

The damaged areas are still wet today but the rest of the driveway has been dry for 18 hours or more. I'm pretty sure they have looked wet ever since this damage was discovered and I rinsed it off. To me that seems to indicate water has soaked a long ways into the slab's fine cracks and much more damage will happen each time the slab freezes after this.

 

[ConCretin]

It's almost impossible to diagnose the cause but it's likely workmanship issues from the original construction. Properly finished concrete isn't adversely affected by water and is pretty resistant to salt after it has time to set. As long as it's air entrained, concrete stands up just fine to freeze thaw. Think concrete water tanks and highways.

With that said, the question is what to do now. Removal and replacement of deteriorated sections is the only permanent solution. Patches and overlays are only as good as the concrete they are applied over. There are any number of products that will stand up over time. We use a product called Ardex CD with good success. Sealing the remaining concrete might help but it will need to be reapplied every so often and won't fix improperly finished concrete.

 

[Stinger]

With some additional research, it appears these fine cracks (likely from excess water) is called "crazing"?

It's almost impossible to diagnose the cause but it's likely workmanship issues from the original construction. Properly finished concrete isn't adversely affected by water and is pretty resistant to salt after it has time to set. As long as it's air entrained, concrete stands up just fine to freeze thaw. Think concrete water tanks and highways.

With that said, the question is what to do now. Removal and replacement of deteriorated sections is the only permanent solution. Patches and overlays are only as good as the concrete they are applied over. There are any number of products that will stand up over time. We use a product called Ardex CD with good success. Sealing the remaining concrete might help but it will need to be reapplied every so often and won't fix improperly finished concrete.

Thanks. As the resident concrete pro here, I was hoping you'd reply.

I've bookmarked my search for Ardex CD and will continue to research it so thanks for that.

In my research the last few days I found another post that seemed promising as well. What are your thoughts on the info here (post #8 in this thread if it doesn't link directly to it)?

Spalling, repair

I have a carport which houses not only my truck but also has an area for my table saw, chainsaw sharpening stuff, etc. I poured the concrete floor probably 8 yr. ago now, and for the first time in concrete work I am seeing spalling in a couple of places, several feet square each. It is about a...

www.garagejournal.com

 

[ConCretin]

In my research the last few days I found another post that seemed promising as well. What are your thoughts on the info here (post #8 in this thread if it doesn't link directly to it)?

Honestly, I've never heard of magnesium phosphate concrete. My guess is that it's fairly pricey and I'd be surprised if it matches the color of your existing concrete very well. It does indicate that it can be be used in thicker repairs and still feather out to zero, which is helpful. It might be worth trying in a small area to see how easy it is to work with and what it looks like.

Just to elaborate on Ardex CD a little. It matches the color of our concrete reasonably well, will take a broom finish and holds up well but it's only for thin overlays. You'll need a different product to fill the areas that are deeply deteriorated.

I'm afraid you have your work cut out for you. There is a reason that concrete repair and restoration is a multi billion dollar industry. There is just no substitute for properly placed concrete. There is no such thing as a permanent repair if it's attached to concrete that's not.

 

[Stinger]

Honestly, I've never heard of magnesium phosphate concrete. My guess is that it's fairly pricey and I'd be surprised if it matches the color of your existing concrete very well. It does indicate that it can be be used in thicker repairs and still feather out to zero, which is helpful. It might be worth trying in a small area to see how easy it is to work with and what it looks like.

Just to elaborate on Ardex CD a little. It matches the color of our concrete reasonably well, will take a broom finish and holds up well but it's only for thin overlays. You'll need a different product to fill the areas that are deeply deteriorated.

I'm afraid you have your work cut out for you. There is a reason that concrete repair and restoration is a multi billion dollar industry. There is just no substitute for properly placed concrete. There is no such thing as a permanent repair if it's attached to concrete that's not.

Understood, thanks.

I saw that Ardex has 3 different products for different steps (filling small holes, skim coat, sealer). The process looks reasonably easy but the idea of trying to do 3200 sq ft without having issues with it drying too early or other issues seems unlikely (for a DIY scenario and not a full crew of pros). I'd assume the proper method would be to do small sections at a time (divided up by each expansion joint) to have a reasonable shot at success. Maybe it dries much slower than I'm anticipating and it's not much of an issue though.

I understand I'm in a tough spot here but considering the cost of replacing this large slab, I feel like I've got to try "something" to prevent or even extend how long it's going to be before I've got to drop $25,000 or so on new concrete (plus the cost of removal of the current material).

Due to the age of the current material, I think any skim coat is going to be a lighter color than what's there but I'm OK with that. My only concern is preventing this from turning into a complete mess within the next few years.

 

[ConCretin]

I'd definitely divide it up into small sections. Your control joints are an obvious place to start but I'd be looking to do pretty small sections to begin with - maybe as small as 50 sf. See what the coverage rate is per bag of repair mortar is and adjust accordingly. You could even add some saw cuts to create some delineation so it looks less like patches.

The first step will be to diligently remove all unsound concrete. Dragging a chain will produce a different tone when it passes across delaminated concrete. Obviously deteriorated concrete will need to be mechanically removed until sound concrete is found. If you still think patching is viable after you see what you are left with, you can proceed with patching.

You'll need a different product to do deeper repairs but you can leave them low and Ardex right over them for a consistent appearance. A bonding agent is advisable for deep repairs. Armitec 110 is our go to product. It's 3 parts and a bit pricey but it has a long working time and encapsulates rusty reinforcing if you have any. It doesn't re-emulsfy when exposed to moisture like the Weldcrete type products. I'd avoid epoxy altogether. You could get by without a bonding agent if the existing concrete is clean and saturated with water (no puddles).

You'll want a pretty flat surface before you apply the Ardex. You'd be surprised how hard it is to keep the substrate from telegraphing through to the surface.

 

[Stinger]

Thanks. Lots to digest there. I'll start researching everything mentioned.