Anyone use "reclaimed concrete"??

[dirtdobber1]

Hi all,

I'm helping a local non-profit group create more parking area behind their facility. They have a very tight budget. I have devised a plan that will yeild about 18 new parking spaces in an area that has an approximate slope of 6%. With a tight budget, asphalt or concrete surfacing is out of the question -- aggregate of some type it will be.

Have any of you ever used "reclaimed concrete", which is how our local concrete company describes the processed / unused portion of concrete that comes back to the plant. Looking at the material, it looks like mostly sand with some aggregate in it. I suppose they somehow wash the cement out of the mix and dump it, and then sell it at a seemingly good price of 6.50 per yard. Any body have any experience with something like this? How well does it set up / compact, likelihood of it washing, etc.?

Thanks in advance for your insight.

 

[CM1995]

The only time I have ran across this material has been where it was used as fill and then covered with dirt. We did a Dollar store that had a 6-8" layer underneath topsoil and grass. The site was in an old area of town, this building was the 4th structure to be on it.

It crumbled easily as we dug it and quickly got mixed into the topsoil and undercut from the site. It seemed to be mostly sand with some aggregate. With a 6% slope I think it would wash, depending on the sand to gravel ratio.

How thick are you planning the "stone" parking lot to be? 4-6"? You might be able to use this material on the bottom 2" or so and then top it with 3/4" crush if you guys have it available over there.

 

[mowingman]

I have used this "wash out" material for some fill projects, and for one road into a small storage lot. It is highly variable in composition and quality from load to load. I would not recommend it for roads or parking areas, as it has very little binder in it. As mentioned, it is mostly sand and does not compact well, nor stay in place well.
Recycled "crushed" concrete is much better and will actually set up hard for a good driving surface.

 

[dirtdobber1]

CM, I was planning a 6" course of material for the parking lot. Until I looked at the reclaimed concrete product this morning, I had hoped it would suffice. However, I'm worried about the amount of sand in it. I can just see it washing to the bottom of the hill after the first big rain!

I may split the difference and use 3" of it under 3" of crusher run. I do plan on trenching in a grid of sock pipe to hopefully avoid some erosion. The parking lot will never see heavy traffic.

Mowingman, you are confirming my fear of this material.

Thank you both for your input.

 

[old-iron-habit]

I have a access road that I built of reclaimed concrete across my wet field to a outer machine shed. I screened out the bigger chunks so nothing over 2.5". At 8" deep it set up as hard as can be. Normally I could not cross when ever we had a bit of rain without tearing things up. It was hard to blade smooth with my 212 Cat after it set for a few months. It sells for $0.50 a yard at the local redi-mix when I load it out myself. However, I would not use it on a parking lot. It tracks terrible either wet or dry. With cars going in and out, I'm afraid you would have grey tracks for a quarter mile up the hiway. I am going to put a layer of recycled asphalt on top next summer as my wife is threatning to ambush me with a broom stick if I keep walking in the house with it on my shoe bottoms.

 

[Tinkerer]

The original post is about the material redi-mix plants create when the returning trucks water down their left-over redi-mix and dump it. The cement in it isn't reclaimed. At least not from what I have seen. Depending on how much water the drivers put in the drum the washout may harden into varying sized pieces of set-up concrete. Or it can be just what the OP described if they are real generous with the water. The hardness can vary because of that. Myself I would not use it because of the cement in it. It could be a nightmare on a wet slope.
Reclaimed concrete is a popular product in my area. It is created by running broken up concrete thru a crusher. The thing to watch for with that product is pieces of re-bar and rewire in it.

 

[old-iron-habit]

I have a access road that I built of reclaimed concrete across my wet field to a outer machine shed. I screened out the bigger chunks so nothing over 2.5". At 8" deep it set up as hard as can be. Normally I could not cross when ever we had a bit of rain without tearing things up. It was hard to blade smooth with my 212 Cat after it set for a few months. It sells for $0.50 a yard at the local redi-mix when I load it out myself. However, I would not use it on a parking lot. It tracks terrible either wet or dry. With cars going in and out, I'm afraid you would have grey tracks for a quarter mile up the hiway. I am going to put a layer of recycled asphalt on top next summer as my wife is threatning to ambush me with a broom stick if I keep walking in the house with it on my shoe bottoms.

I misquoted. This is wash out material. The screened out chunks were the hard concrete sections that were left in the truck.

 

[muskoka guy]

I have used it as road base on several occasions. As the stuff I used was mostly gravel in the concrete, it worked great. It remains very messy if it rains and I only used it as a sub base and covered it with good gravel. It sets up pretty hard after a while. I used it around some culverts and it worked great. My one culvert froze up last winter and the creek ran over the road for several days until I could get the culvert unfroze. The washed concrete never moved an inch. Would definitely not recommend it as a topping for anything.

 

[hmearth]

I use recycled concrete all the time and prefer it over most other materials.
We get crushed down to 40mm and pust it out 200 mm thick plenty of water and a pad foot roller the roller will walk out of it quick grade it to level flat drum with some water and stay off for a few days and you will not bet as a percentage of the cement reactivates give a real good base

 

[cdm123]

The material used for concrete has a very low clay content, also a good driver will add as much water as they can because no one wants to be in a drum with a hammer cleaning out the built up concrete!

 

[ericscher]

My personal feeling, and I know that not everyone will agree, is to do the following:


1. excavate 4-6 inches depending on where you want the surface of the parking are to be in relation to the surrounding area.
2. put in 4 inches of #411 limestone, smoothing, leveling and compacting each truckload as it is tailgated in.
3. add 2 inches of #57 limestone, doing the same.

The 57's will cut down on dust dramatically as well as the sort of sandy-looking mud you can sometimes get with just 411's when it rains.
Women REALLY care about this. Just sayin...

All this assumes that this is a relatively light-duty lot that mainly sees automotive use (cars & light pickups), not trucks. If the usage if heavier, such as if the area is heavily biased to big SUV's and full sized pickup trucks being used for transportation, then go down another 2-3 inches and add a layer of #2's.

I am also assuming that you get down to clay, either way. If you are still in the loamy soil type of dirt then put down a layer of woven Geo-Textile before adding stone.



This DOES a add a bit of expense up front as compared to using reclaimed concrete, but like many thing you make up for the up front cost in lower maintenance costs year-over-year.


One other option is to use grindings (recycled asphalt) but there are issues there:
1. The price is best in the spring and summer when roads are under active repair and the supply skyrockets.
2. It comes in two types, "Once processed" and "Twice Processed". The names may vary but the issue is that the single process stuff may have surprisingly large chunks in it that have to be removed.
3. To properly compact it you need a proper dual-drum vibratory roller in order to get the density and surface hardness that will give you a reliable and clean installation.
4. Once it's in it really isn't practical to groom it like a gravel lot. Your options are to add more and re-roll, or tear it off.

 

[hmearth]

The material used for concrete has a very low clay content, also a good driver will add as much water as they can because no one wants to be in a drum with a hammer cleaning out the built up concrete!

The recycled material we use is usaly no clay because at the plant if you take concrete in there covered in dirt your rejected and have to go to land fill.
But you will still need to use a pad foot roller (not a flat drum) reson being if you have test it for compaction it will fail every time

 

[JNB]

The 57's will cut down on dust dramatically as well as the sort of sandy-looking mud you can sometimes get with just 411's when it rains.
Women REALLY care about this. Just sayin...

I agree, and it's one of my best selling points. We have a 3/4"-to-chat size crushed limestone here that I top almost all of my driveways with. It's unwashed so it has some fines in it. It locks in really good and looks great.

Around here, the term "flex base" is used to describe everything from pea gravel with fines to 1.5" with fines. They're all caliche based which gets milky white when it's wet. For hillsides driveways or those requiring cross-drainage I use the 1.5" version with a topping.

This DOES a add a bit of expense up front as compared to using reclaimed concrete, but like many thing you make up for the up front cost in lower maintenance costs year-over-year.

On this I have to disagree. I use a lot of concrete washout for road base. It does differ from typical reclaimed concrete in that its nice and clean...no clay, plastic chair pieces, visqueen or rebar. Top the washout with 3/4 minus and it ends up being a good looking driveway with an extremely hard base. I have a whole bunch of driveways out there several years old that still look great with NO maintenance.

 

[ericscher]

On this I have to disagree. I use a lot of concrete washout for road base. It does differ from typical reclaimed concrete in that its nice and clean...no clay, plastic chair pieces, visqueen or rebar. Top the washout with 3/4 minus and it ends up being a good looking driveway with an extremely hard base. I have a whole bunch of driveways out there several years old that still look great with NO maintenance.

I don't think we so much disagree as we are looking at different ways of HOW the concrete is used.

 

[diggerdave1958]

I use the "washout" on a job for a new township sports field the parking lot was 66' x 1506' we strip the topsoil and then put down woven fabric and about 12-15" of the washout total of about 4500 cuyds we work with 2 local concrete suppliers we had our old JD690B excavator to load out the material and used 3 or 4 tri-axle dump truck to all the material to the job and it work out very good after the washout was down we put on a topping of 6" 22A roadmix (limestone) but each load can very it all depends on how much water is added to the truck when they washout at the end of the day, some was a nasty "mud" and then some was almost a sand/stone mix almost like roadmix. I would use it again anyday !!!!!!!!!