Rain damaged concrete driveway/gravel erosion from under slab

[luckyduck]

I hope someone can advise me on a few things. I had a concrete driveway installed last August. There was a forcasted thunderstorm the 2nd day of construction and 1/2 of my driveway is damaged with significant pockmarks and lose of form at the expansion joints. They didn't cover the concrete with plastic and I wasn't knowlegable at that point to request it. The surface continues to flake off. It has taken me 9 months to get the company to respond to me, and they want to apply Miracote. I feel I spent a lot of money for a concrete driveway and this is just a bandaid on the problem.

Secondly, I have a car turn around in back of the house. Gravel has eroded from under the slab. You can feel movement in the slab when a car backs up over it or if you stand in the middle and jiggle. This is on a steep hill and I worry that the slab will break/crack or it will slant to the point of being unsafe.

Thanks for enduring this long post. I wish I had gone with ashpalt.

Jenn

 

[boo1]

After the concete placed and hydrated (hardened) rain will not affect the strength only the surface appearance. The slab movement sounds like the soil base washed out or was improper compacted. Kind of scary!!

The MIRACOTE® Cementitious Coating System is not a paint but a cementitious protective coating which consists of a unique rubber-like polymer liquid. It is a resilient surface that will last for years with little maintenance.
Miracote provides a tough water-retardant coating which substantially reduces or prevents water penetration, freeze-thaw scaling, and concrete carbonation.

What are they planning on doing about the slab movement?

 

[luckyduck]

Thanks for the reply. As far as the slab is concerned, they want to use topsoil to keep more gravel from washing out. I don't consider this a satisfactory repair. They are implying that I should have had topsoil brought in immediately after the driveway was constructed. I never thought of topsoil as a stabilization tool. I had every intention of having a landscaper come and repair the yard after they tore it up, but wanted to wait until we had established a resolution on the rain damaged part of the driveway and do the entire yard at once.

I consider concrete to be maintenance-free...is Miracote also maintenance-free? Is this the most common way to fix rain damage? Do you think it appropriate for the concrete company to pay for the repairs?

Thanks again for your help! This is a great forum!

Jenn

 

[sc]

I would have thought that the concrete construction company would be liable for costs of repair/replacement, as they have clearly failed to protect the freshly poured driveway until satisfactory curing had taken place.

As a person who has supervised concrete works that have been affected by rain, I have had concretors pull out rain effected concrete where the surface finish has been compromised from what was required. They didn't like it but they weren't going to be paid until they did it. I don't believe that a surface treatment will last as long as concrete, however, it is still a legitimate repair.

Another way to repair the surface may be to have it ground back, I'm not an expert on how rain effects the surface or to what depth, however, I would think that a surface grind approximately 5mm deep (maybe less) would be sufficient. This depends on concrete-reinforcement cover and the depth of the slab as to whether it can be done or not. This would leave the surface with an exposed aggregate look.


regards
sc

 

[boo1]

top coating the surface should leave you with a good surface. But the movement when you drive on it, is no good.
Removing and replacement may be required.

 

[RDK]

There are two issues here. The first is the rain damage. As others have stated its mostly superficial and with a proper coating this would be an acceptable repair method. I’m not familiar with the one mentioned but others appear to have faith in it.

The second is the gravel wash out. Topsoil will provide a barrier to stopping the gravel from being washed out. So will a number of other barriers. Such as wood or concrete curbing, metal or plastic lawn edging. The purpose of these barriers is not to support the concrete, merely to prevent gravel erosion form occurring.

Did you contract with the driveway firm for a complete job including rough landscaping? If so then this was the driveway contractors responsibility, if not then its your responsibility. Unless you specifically contracted for the edge protection you are most likely responsible for it and the consequences of not having it.

In either case I would recommend you look into a repair method called slab jacking or mud jacking. This involves drilling a 50 mm hole in the concrete and pumping a slurry grout under pressure to full the voids and raise the slab. A driveway could be done in an hour or two depending on the area and last time I had this done (fall of 1999) it cost $Cdn 150 per hour. (Approx. $US 100).

The edge treatment should be done as soon as possible to prevent further erosion (as in do you have plans for this afternoon?) and you should stay off (i.e. cars and heavy loads, ok to walk on it) the driveway until its supported to prevent further structural damage.

If any significant cracking has occurred then the cracks should be sealed to prevent moisture from entering and causing freeze-thaw damage (if this is a concern in your area)



Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[Ron]

You mentioned that concrete was still "flaking" off from the rain damage. This implies more than just an aesthetic issue. If this is still occurring, then you likely got enough rain on the surface to increase the water-cement ratio in the upper 1/4-inch or so. This is a durability problem for the long term, especially with the abrasion of vehicular traffic (albeit light vehicles).

In order for a topping to work properly, you must remove this laitance effect at the surface before placing the topping. In short, if the topping is done properly, it might be as expensive to the contractor as removal and replacement!

As for the washout, topsoil is not a stabilizer for conditions such as this. In this case a thickened edge slab would have been a better option to contain the gravel. Since you now have the issue, a separate retaining, flush curb should be used. When place, the concrete for the curb should be flowable enough to flow under and fill the edge voids and provide edge support for the slab.

 

[luckyduck]

I appreciate everybody's expert advice. I plan on sharing this information with my concrete man this week. It should be interesting!