Drying Clay 5

[isaacsdad]

I am building a fill on an earthen dam the core material by spec must have a minimum of 50% passing a 200 sieve a clay material. Problem the excavated material on site is registering 22% moisture and optimum moisture is around 13% it must be dried to build this fill. This is an open cut of an existing reservoir to install a pipe. The work must be completed by the end of February so simply waiting for dryer weather is not an option.We have explored the possibillities of using a portable drum dryer but the local environmental requirements would take months to obtain a permit. Trucking the material to a hot plant for drying is costly. Any ideas would be appreciated

 

[KRSServices]

Wow, talk about a rock and hard place! You may want to consider laying out the borrow on the section of dam you wish to build using buggies and then disk it once or twice a day, or more to promote faster drying. Depending on the abient tempurature and relative humidity, it should work, but I will conceed that it wil take time.

I've used this technique on roads many times and it may work in your application.

KRS Services

http://www.krs-services.com

 

[Leongoring]

Is it possible to:
1) When disking as suggested by KRSServices to introduce additional dry material so a blend is obtained that fits the specs and reduces the moisture.
or/and

2) Can a hygroscopic material be disked in to reduce moistute eg cement say 5% by wt. (dependent on volumes involved), lime (calcium ?? - forgot my chem here!) or suchlike material.

 

[isaacsdad]

Thank You All for your suggestions. I am Told that The department of dam Safety does not encourage changing the chemical composition of the material, but it has been suggested. We have began searching for a dryer material that meets our specifications, either to introduce to the existing or replace it. Calcium seems to be the front runner in material to create heat and promote drying and hardening of the material.

 

[Rockjoint]

Would heating blankets work? I have seen them used in upstate New York to dry silt and clay that was wet during winter conditions, and it performed very well. Seems like the system used recirculating antifreeze liquid that was heated and pumped through lengths of hose/blanket combination.



Rockjoint
rockjoint@yahoo.com

 

[RockDr]

Quicklime (CaO) can be used to 'dry' the material. The concerns with using lime is usually that the material is not hydrated properly upon mixing with the soils and therefore creates a potential for heave.

The drying effect is actually that the quicklime will modify the LL nd PL typically reducing the PI and increasing the OMC. There also is a Pozzalonic reaction that takes place dependent on the percentage of lime applied. This reaction creates a 'dirtcrete' that will continue to gain strength for as long as 6-9 months.

Lime reacts similarly to soil cement however the lime treated material can be excavated and recompacted and maintain the strength gains.

For more info

http://www.lime.org

I have mixed approximately 500,000 CY this past of everthing from CH & MH to SM & SC material and benefitted from being able to work continueously during the wettest year in history in the Washington DC area

 

[GeoPaveTraffic]

I would not recommend adding lime to any fill being placed in a dam. The problem tends to be that the lime will dry to far with time and crack. A crack extending through or partially through a dam, from upstream to downstream, can lead to a piping failure of the dam.

Typically dam specs require the core material to be compacted just wet of optimum moisture content. How far wet is a matter of debate and is also influenced by the height of the dam.

 

[Focht3]

I agree with [blue]GeoPaveTraffic[/blue] - don't use any chemical additives to dry out the soil. This applies particularly to quicklime. Not only is it dangerous to handle and difficult to apply evenly, the reactions will go on for years with many unforeseen consequences.

The core should be constructed of unmodified clay -



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.

 

[isaacsdad]

Thank You Lime would dry out the material but will also change the plasticity of the material. The spec requires optimum plus 3 percent on the moisture. Currently material is at roughly 22% optimum is 12.5% I need to be 15.5% We are currently weighing the options of trucking the material to an asphalt plant 20 miles away, running it through the drum dryer and trucking it back to the sight. We are also searching for an alternate source for the clay fill. Thank you for the suggestions. Please keep up the suggestions.

 

[vicman2]

Why not dry on site using a propane fueled portable ashpalt plant? Most large paving contractors have these available. They ususally conform to most enviromental requirements. If the temp drops below freezing at night, you can use small lifts and discing to dry the material. This assumes that the relative humidity drops as well.

 

[Grouser]

If you have a large enough relatively flat area, you could spread the material and use jet driers like they use at stock car race tracks to dry the pavement. Maybe a train of disks and driers could be used, possibly followed by a dozer or grader to re-windrow for another pass of the train. It sounds like an alternate source for the clay is worth exploring.

Good luck.