Tank Foundation Question

[TANKO]

Good Evening everyone
i have a technical question about the foundation.
Where i'm working the client is using a kind of bitumen emulsion on the sand as final layer. In the civil drawing i read "50 asphaltic sand" as final layer. From my point of view the procedure of the client is not correct infact the result was a foundation with a coloured black sand but soft so i think that they have mistaken the proceudure. As mechanical contractor, according to Api 650, we must check only the concrete ring level and the internal slop and not the quality of the material of the foundation but i'm worried that they are doing something not good.
Can someone give me some information how to prepare an asphaltic sand and its method of application?
Because they are simply pouring the liquid emulsion on the sand of the foundation. I'm thinking that the asphaltic sand is as a mix of bitumen-sand according to appropriate percentage and applied simultaneously with a compactor.

I'm waiting for your response.
thank you very much

regards
Tanko

 

[IFRs]

If there is a proper ring-wall designed knowing among other things the shear strength of the sand fill and the soil under the sand is properly engineered, it should not be not necessary to do much with the sand.

 

[MJCronin]

It is my understanding that the use of a liquid bitumen layer beneath the tank bottom is considered as an older and "hit or miss" method of protecting the tank bottom.

Asphault impregnated board is now more commonly used in tank construction.

http://www.eng-tips.com/viewthread.cfm?qid=359944

http://www.ast-forum.com/ast_forum_tree.asp?master=9806

http://www.carmagen.com/news/Publications/Corrosion.pdf

MJCronin
Sr. Process Engineer

 

[TANKO]

First of all thank you for your answers but beyond the usefulness of using this product i was curious to know if the application procedure was correct which is to pour the emulsion directly on the sand bed....for me it's strange because the result was a black colored sand not a bed of asphalt as a consequence i don't understand which is the meaning of this procedure.
regards

 

[CarlB]

Irving E. Boberg, in the publication "Oil Storage Tank foundations", discusses preparing an oil-sand layer under a tank. It says to mix the sand, not just pour the oil.

http://www.slideruleera.net/foundations.html

 

[TANKO]

Thank You very Much CarlB....i was right about the incorrect procedure. I'm working in tanks constuction but i'm a civil engineer so i have some knowledge about it.
regards