does sand cement slurry penetrate gravel base ? 1

Yes. Journal article not necessary

place geosynthetic or 8 mil poly in the bottom to separate and your problem solved

What is the gravel like? What is the slump of the slurry?

If it is an open graded gravel only, then it will penetrate upto a couple feet depending on the size, gradation, and shape of the gravel. If it is a sand/gravel mix, then it should only penetrate a few inches.

If your vault is big enough, it should be such that it will still drain even with some slurry penetration around the edges.

This is not a journal or calculation thing. It's just experience and common sense. Slurry is a fluid. The soil at the bottom is a sort of filter. The more viscous the fluid and the tighter the filter, the less it will penetrate. The opposite is true with less viscous and more open respectively.

What is the exact definition of "gravel". - There many factors like gradation and particle shape.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.