Site made concrete?

[Al F. Furnituremaker]

I have a early 1930s house. Portions of the poured concrete basement walls and floor are breaking apart. From the looks of things this has been going on for many years. None of it is structurally significant yet. I'm assuming the concrete was site made using the material dug for the foundation, dirt and rocks. No nice clean sand and sized gravel. The rocks are many different sizes and sometimes there are pockets of dirt. I remember seeing concrete mixers specifically made for this.

Has anyone else experienced this? I'd like to fill in/patch the problem areas, but not sure if there is a specialty product to use. I don't even know what to call this kind of concrete so I can do some research. My first house built in the 60s had the same problem in places.

A nice new poured concrete foundation would be great, but not in the budget.

[phil]

you might look into using hydraulic cement, you should be able to get it at any big box store. I guess technically it is hard and maybe not compatible with soft mortar but for cracks in cement it should work good.

the difference is that it expands a little as it cures. you can chisel out a bit to clean the crack then pack it in with a trowel.

https://www.youtube.com/watch?v=pSjNx952uz0

[GibsonGM]

you might look into using hydraulic cement, you should be able to get it at any big box store. I guess technically it is hard and maybe not compatible with soft mortar but for cracks in cement it should work good.

the difference is that it expands a little as it cures. you can chisel out a bit to clean the crack then pack it in with a trowel.

https://www.youtube.com/watch?v=pSjNx952uz0

Yes. Can you post a couple of pics, Al? Just for curiosity's sake. Hydraulic cement works very well for this type of use, but be aware that it's really pretty...caustic...it'll eat up your hands in short order. Wear gloves. Also, it sets up VERY quickly, so mix what you can use in about 2 minutes, and tool it fast, don't keep messing w/it. You'll see.
Good stuff.

[Al F. Furnituremaker]

I will get some pictures but I don't think hydraulic cement is the answer since the surface is falling off and leaving just a large scab. I believe hydraulic cement is for holes and cracks, not slabs as there is nothing for it to compress against.

[GibsonGM]

If it was that bad, on the floors I would test outwards til I find solid 'crete, then cut out the bad stuff, and do a 'localized pour' or some home-made stuff.

For the foundation wall, same thing, but of course you need to be cautious that you don't open a huge can of worms! Sounds like maybe the site sand/etc may have contained a salt or something, perhaps...causing early failure. Or maybe some localized freezing (?).

I'd use a "pointy chisel type thing" to test around, see if this is just an a few small places or widespread. If small areas, you could dig some out and apply a bonding agent, then just parge them up with a rich mortar mix.

[phil]

the expansion rate isn't huge or anything. and there are different types of hydraulic cement. for example this one is recommended for skim coating cement.
http://www.forconstructionpros.com/prod ... -skim-coat

I'm not a cement expert. If it's no rush I do know an older Italian cement finisher and he's retired not but i see him occasionally so I could ask him or if it is a hurry, I work with lots of carpenters who teach the basics and they are all tradesmen and instructors. This hydraulic cement gets warm and it sets very fast. it's what you want for a crack in the foundation or sometimes they use metal strapping in the formwork for foundation walls and that rusts out eventually and causes leaks. It may be suitable for skim coating but if you have lots to do it might be worth finding out a little more. It does say to avoid applying it over V shapes because of the slight expansion but that's what you want if you are putting it in a crack where water is coming in. Best if you can attack that from the outside but that isn't always possible without digging lots. if you did it might be worth putting a membrane or some tar or something similar as well. I have used the hydraulic cement a few times and didn't ave issues with it popping off or anything, it really stuck well.

if it is just roughness you could look into using epoxy as well as it sticks super well and it's hard once it sets. I happened upon 10 gallons of some free stuff that was from a cement finishing place, also I have about 10 gallons of a product used for filling cracks, maybe for expansion joints. it is also a two part epoxy. I forget the brand just now but here is a link to a similar product. it allows some movement as it is slightly flexible. if you contact whoever sells finishing products to concrete industry in your area they could advise better in this area. You may not be able find this kind of stuff in the big box places. commercial finishers are expected to handle them properly but I think places like HD might worry about liability and maybe there are legal issues for not selling products that they feel may require better than average home use personal protective equipment for safety. its common to do repairs in warehouses where the floor gets roughed up and the forklifts are heavy so they may shift sections of the floor as they run over..

http://www.altro.co.uk/Flooring/Floorin ... g-compound


this site has some products for that.
http://www.sakrete.com/media-center/blo ... d-Concrete

I think you are going to be limited to what is available but a cement finishing products place that sells to the commercial finishers is going to have stuff they have used and recommend. If you need smaller quantities or if they won't sell to the general public then maybe a cement finisher could provide less as it's probably going to come in 20 l pails for commercial use. An epoxy may level itself quite well on floors but on walls it would run down.

I bet if you asked in HD they would sell you an inferior product designed for home use. so for the best advice I wouldn't start asking questions there. I'd find a commercial finisher and maybe go in the back door and take a couple plastic containers and maybe they will just pour some off for you in exchange for a case of beer as a favor if they feel like being nice.

[Al F. Furnituremaker]

Thanks Phil. It's no rush so if you stumble across the guy ask. I always thought hydraulic cement was for places it could expand into and fit tight. I was thinking of some kind of self leveling product for the floors, but the walls as the first thing to tackle.