Site drying with unhydrated lime

We have become aware of unhydrated lime drying techniques over the last two years. There was some good lime info at CarmeuseNA.com but the last time I went to the site it was down so I don't know if thats still a good info site but key word search for unhydrated lime or lime drying may be productive.

In two situations, the lime has allowed us to dry a roadbed sufficiently to pass state or county compaction and pave during a rainey cold period.
In both situations, the lime allowed a stalled project to be completed.

The most recent situation was 700' of a 3200' county road went through a valley with no sunlight all winter. Rain was spaced every three to four days and it wouldn't dry. We applied 15 tons of unhydrated lime to that section and passed inspection the next morning. The lime cost about $1500, took 3 hours to apply and work, and opened a housing development for far less than the debt service on the property.

For those of you who have not seen this work, here is some background.
Unhydrated lime is not agricultural lime. Its a lime that has been kiln dried.
When the unhydrated lime is tilled or disked into mud, there is an impressive chemical reaction during which the water is boiled out of the dirt, the dirt molecules are rearranged in a process that is similar to concrete setting up, and in several hours a hopeless site can be going again.

In soils of marginal structural character, application of the kiln by product, fly lime can often improve the structural characteristics of soils cheaper than digging out and replacing deficient soils.

I would be glad to share our experiences with any curious members but there are several areas where I would appreciate input:
1. Since this product is similar to talcum powder, we use a dumptrailer to transport it, buy the rice grit to minimize blowing, super snug the tarp and roll.
Since our method requires no rain during transport ( the impressive chemical reaction I mentioned can melt your truck), although most folks transport lime in trailers like dry concrete uses, I was hoping to get some transport insights from the other members.

2. The tools of choice for mixing the lime with soil for big sites are huge 800hp tillers that mix the lime to 18". For smaller jobs, we have employed tractor powered tillers and knife and disk harrows to mix the product.
Any insight into mid size tiller or other tools that you guys have seen that are more agressive than farm tillers but smaller than the 800 hp units?

3. We are getting our unhydrated lime from south of Birmingham which is a 400 mile round trip from North Georgia. Anyone familiar with any limestone quarries ( the ones where it always looks like it just snowed) in Western NC, Eastern Tennessee or North Georgia,...please advise.

Thanx

alot of the job sites around here are lime stabilized. its a good product im not sure it works quite as fast as you belive.. but it may be a bit different depending on the lime make up. but yes within 24 hours usually the ground is hard as a rock. theres a place in southern indiana near evansville that has a large supply of lime. i cant rember the name of the place off the top of my head. ill have to look for the info at the shop tomorrow. mt carmel maybe.. im not 100% sure tho. company name same name of city near evansville. so it may be worth googleing it.

my personal feeling bout it.. i dont wanna be no where near when its put down. they **** is nasty. and theres been some studies that its not the most healthy thing to be breathing in and out.


payton

I was wondering about the environmental concerns in reading this thread. The EPA has no problem with this practice?

Steve Frazier said:

I was wondering about the environmental concerns in reading this thread. The EPA has no problem with this practice?

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as far as ive been told theres no real impacting issues with the practice of lime.

farmers have been using it for years and years around here. the only real issues are the inhalation of the stuff it is pretty nasty stuff.

I've read that you need to pay attention to where the wind might carry the dust too. Apparently it upsets the neighbors to find their cars dusted with lime.

Mo lime

The EPA is OK with lime used as previously described. ( that was the first question at the seminar I attended before we began to use it.) They are actually postive toward it because it shortens the time the site will be unstabalized, and reduces washing.

It is tricky to transport as fines so we use the rice ( lime in rice size and color) because it is easier to transport and less dusty when applied.
Just as gasoline, firearms, and driving a vehicle require proper respect and appropriate handling, lime does too, but it is far from unmanageable and it can get you paid sooner or solve bad dirt problems when used on many projects.
Here are a few observations we have made.
If you don't have to be close, don't be.
If you have to be close, wear long sleeve shirt, gloves ( like when you install fiberglass) and a filter mask.
Let the applicator truck and the tiller make the application before you enter the site, at that point the filter mask and long sleeves are often discarded because the lime dust is underground.

The lime will continue to sweeten overnight if left exposed. It will get even harder than necessary for compaction. It will pass inspection several hours after application. It can be paved the same day. It will get even harder overnight.

Cheers

Hi everyone,

I'm bumping this old thread up to hopefully gain some insight on some techniques that might be employed to get the moisture content down in soils for compaction. This has been one wet year on the east coast and I was wondering how some of you might be dealing with it?

Thanks in advance for any info.

rustyjames said:

I'm bumping this old thread up to hopefully gain some insight on some techniques that might be employed to get the moisture content down in soils for compaction. This has been one wet year on the east coast and I was wondering how some of you might be dealing with it?

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I was halfway through the thread before I noticed the date good info never dies, well reserected.

Soil stabilisation is BIG in the UK and I am sure stock will confirm its used a far bit in Ireland also.

BUT BEWARE. A few years ago a UK contractor caught a cold using the stuff on a major earthworks contract.
The original soil samples in the borrow pits missed a chemical. I wont pretend to know what it was but it was not dangerous, something quite benine it just did not like lime
The chemical reaction after construction caused the ground to swell and expand pushing great waves up into the completed carriageway renduring it completely unusable.
Cost an awful lot of money to put it right.

It is a very good method of drying up ground to allow work to progress just be aware that not all soil types are suitable for mixing with lime.

Atlas,

Thanks for that piece of info, it's something I never even thought about but definately something to consider.

Just curios, Does the lime have to be kiln dried to stabilize soils ?

Around here they put lime and water and egg beat it in then waht 2 days and come bacj and put half the amount of Coal fly ash then they do the same thing with it that they did withthe lime . have also hauled flyash to old oil pit and blowed it in the puit in order to dry the pit up

Yes, flyash will work as well but around here they worry about about groundwater contaminaion; even if the site is already contaminated.

BIGDAN315 said:

Just curios, Does the lime have to be kiln dried to stabilize soils ?

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The kiln dried lime is required. The way it works is when the that kilned is mixed with the soil, it creates a chemical reaction. It requires moisture. Once the lime gets wet it begins to heat up. As the reaction continues, the lime crystalizes. That is where the stabilizing comes in, the heat created from the reaction is what causes the drying.

rustyjames said:

Yes, flyash will work as well but around here they worry about about groundwater contaminaion; even if the site is already contaminated.

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Then if that is the case, I would look at portland cement. You can sell the portland as a way to encapsulate any contamination and keep it from entering the groundwater. This way you get officials to go for it, and you solve your stabilization needs.

Turbo,

Good point; I guess what it comes down to is what's the easiest to obtain and what's cheaper.

As busdriver said we us it a lot in East TX not many roads parking lots are built without it. They make all different sizes of mixers and we have put it in with ripper, disk, or just even spread it around with a dozer. Unless the job is a total mud hole we use lime that is mixed in water it comes out of the truck like a sludge. That keeps the dust down and if the ground isn't wet enough ya don't have to add water. I don't know a much about other then that. I'm not saying its good for you but no safety issues have ever been brought up when using it.

Dozerboy said:

.............. Unless the job is a total mud hole we use lime that is mixed in water it comes out of the truck like a sludge. That keeps the dust down and if the ground isn't wet enough ya don't have to add water.

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I have encountered most of the methods you mention for mixing, it seems to depend on whether its a major contractor or a small back street outfit and the equipment available as to the method used but I have never seen or heard of the sludge from the tank method.

Ya its the catsa$$ out here no lime dust blowing all over the traffic lanes during road work. I wish I knew more about it, but its not something I mess with often.

Ive never worked with slurry, but im sure its cats ass when you are in dry material. The worst part of lime stabilization is the dust. I swear that stuff goes through glass. Not to mention going every where. I would like to learn more about the slurry option, anyone here use it?

A friend of mine makes lime slurry at his yard for a large stabilization contractor out of Mt Carmel IL. They kind of use him as a satielite yard for the St. Louis area. They mix it in a large stationary mixer where they add the water and bagged gymsum. I don't know what the gymsum does I just remember seeing them dump it in. They told me that the lime they use is over 90% code L so the consetration is alot higher so you don't have to use as much to achieve your target %. If I remember right standard lime only has to be 70% code L.
Mt. Carmel has this down to a science. They use custom built trucks that they tow behind their mixer and pump the slurry directly into the mixer drum housing as they mix.
I have also seen them put it on a tandem dump that has a auger type distributer on the back. Never seen it in action though.