Mixing concrete powder into the gravel - driveway

[Tractor_Jim_CT]

I was wondering if anyone tried mixing powder concrete with gravel or spreading concrete powder on top and mixing together with a rake, then spray on some water.

Sounds crazy, just a thought.

 

[Darren]

In the past self-propelled tillers have been used to mix cement and soil to strengthen highway subgrades. For a regular driveway, I find crush and run #57 rock contains the right mixture to compact well and resist traffic.

I don't think you'd get any benefit out of the cement because of the small amount of cement for the thickness. If you use enough cement ... you'd have concrete anyway except it would not be mixed uniformly enough to do any good. You could treat your driveway as one long mud pan and mix the concrete in place. It would be a lot of work for a driveway of questionable strength.

 

[KiotiJohn]

Jim, you need to go back to your repeat post and hit the edit button, and then delete it. thanks, John

 

[Egon]

For soil cement the CRUSHED gravel should have poper mix of fines to larger pieces to make it as dense as possible.

Add the proper amount of cement and water and mix well by some mechanical means, smooth to grade and pack it.

The mix is not a slurry and is very hard to tell from damp gravel. A seal coat over the top will also help for longevity.

Expect cracks and seal them as soon as possible.

Unless the proper amount of cement is used it will be a waste of money. The best soil cement is mixed in a plant just like asphalt but without the heat and then hauled to the site.

 

[gsganzer]

I've done this. I don't do it for strength, I do it for dust control. The cement mix helps bind up all the "fines" and keep down dust.

 

[Bob_Skurka]

Jim, take a look at products like "Polypavement" and some of the other brands (do a google search on soil binders and similar terms).

There are numerous brands out there that do work to bind together the soil into something that seems to be a rough equivalent of asphalt, and is something that a do-it-yourselfer can handle. Some brands need clay content in the soil, some are for stone, etc. Be careful to read what the various brands need because if you are going to use it for a stone driveway then you'd want one of the brands that does not require clay content to bind the material. All the brands I looked at seem very cost effective, and if done right sure appear to be durable.

Here is a link for the brand I will probably be using to make solid surface paths in my woods this summer. It might be the wrong brand for your needs but it will give you a good idea of the process. It seems like you could use a product like this to turn a gravel driveway into a solid surface stone drive that would last for several years before needing to be redone. PolyPavement Website Personally, if I had known about this stuff 10 years ago and it lasted for 3 to 5 years without the need for repair, I'd probably still have a gravel drive instead of asphalt.

 

[Highbeam]

We call it concrete treated base here in the NW. The commercial developers use it beneath the pavement section when they are putting a road or parking lot on top of an old farm. It is just a base to support the flexible pavement, not a seal.

1/2" of cement tilled down to 14" (the mix is supposed to be 6% cement) into the native soil. They use this monster caterpillar tiller to do the job in a day. The tilled material is then graded out smooth. Now is where it gets tricky, some engineers call out crushed rock and then asphalt, some just put the asphalt down on top of the CTB. I think I would rather go for a layer of crushed first.

This method is taking off like wildfire. It firms up the subgrade enough to support 80,000 lb semis with a 3" layer of asphalt. It also works in the winter since the PCC just gets tilled into the mud.

If you do not intend to seal off the surface then there is a chance that water will not be able to go through the CTB and then you would need to grade a crown into the CTB before adding gravel.

Be sure to put in all your utilities before placing the CTB. It sets up like CDF, a weak concrete, and will make trenching difficult.

 

[Tom_H]

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I assume that you mean "Portland Cement" which is made of limestone, clay, and sand cooked together then gypsum is added. This is the "binder" in the concrete and composes 7-15% of the total concrete weight. The rest is aggregate: sand, gravel, etc. When you order concrete delivered by truck, they ask "How many sacks?" This means how many (usually 80 lb.) sacks of Portland Cement do you want mixed into each cubic yard of the concrete. Typical mixes, depending on application, will be 4 sack, 4.5 sack, 5 sack, 5.5 sack, or 6 sack mixtures. In addition to the normal aggregates, for an extra cost you may add flyash or volcanic pumice to increase density and reduce porosity, fiberglass or HDPE fibers to prevent cracking during curing (these can substitute for rebar), coloring, etc. Water content varies depending on outdoor temperature and other factors. Special mixes for special applications include things like Gunnite to build swimming pool walls.

Dry, from the home center, you can buy just Portland Cement in a bag, or you can get "Ready Mix Concrete" which is a small percent Portland Cement already mixed together with the aggregates.

Brick mortar is Portland Cement and a specific grade of sand blended. Again, you can buy "Ready Mix Mortar" if you don't want to mix it yourself.

You can get a number of special mixes at the home center as well as additives such as liquid acrylic to make the product stronger and reduce porosity. Some mixes are designed to be applied dry. An example may be a prepoured concrete anchor that is already in the ground for a metal post. The anchor has threaded rod to which the post is secured with bolts. Then the volume from the bottom of the post to ground level may be packed (as in hard tamp packed) with a dry mix concrete which absorbs moisture from the surrounding environment and then cures.

 

[DaMadman]

I dumped a couple bags of sak-crete at the end of my driveway just a couple weeks ago when I dug the culvert pipe out and put it back. We had a lot of rain before and during the time I was doing this and the edges of the driveway were stay really mucky, so I dumped two bags of sak-crete into the muck and let the moisture in the mud suck into the mix.

The edges, within two days were no longer muck and are very hard and stable now

 

[Highbeam]

Regular quickrete is a mixture of 3 parts gravel, 2 parts sand, and 1 part cement. So only 15% of that sack is the good stuff.

You can buy plain old portland cement. It is nothing but a fine powder. Till that in and a little will go a long ways.