Specific Requirements for Mud Mat?

[structure567]

I have a question regarding the use of Mud Mat to meet the design excavation level.
I am working on a deep foundation that is laying on slightly to none weathered bedrock. The excavation involved blasting which resulted in some areas that were over excavated approximately 5 feet below the design elevation in which the foundation is suppose to sit on.
We will be filling the gap with 3000 psi concrete acting as a mud mat. I'm trying to find out if there are any specific standards to follow for the design of mud mat. Although this concrete is purely acting as filler for overexcavated areas, it is still pretty thick for a blinding layer and will be poured in an area that will have water due to the high water table.

 

[SlideRuleEra]

...mud mat...will be poured in an area that will have water due to the high water table.

Dewater before pouring concrete. Depending on ground water conditions, this could be as simple as short-term use of (diaphragm, e.i. "Mud Hog") pumps all the way to using well points or deep-well pumps for duration of foundation construction.

 

[JedClampett]

I've asked the same question and got the answer "a mud mat is a mud mat." What I've sleuthed out is it's close to a flowable fill, slurry or CLSM (controlled low strength material). A 3000 psi mix will work, but so will a one sack slurry (strength 100 psi).
As far as design, it's make up layer, unreinforced. Five feet is a lot, but I've poured many feet more (in four-foot lifts) for settlement reduction.

 

[structure567]

Thanks for the responses. Is there any preference to using CLSM over normalweight 3000 psi concrete?

 

[dik]

It may be less costly, but can generally be used. CLSM often comes in a variety of strengths.

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