Why corpses do not float up in concrete, while concrete is still liquid and not yet solidified?

Question

Density of concrete is about 1.8-2.3 times that of water (and hence that of victim's body).
http://hypertextbook.com/facts/1999/KatrinaJones.shtml

Answer 1

Viscosity is basically correct. The corpse won't sink either; you'd have to poor the concrete over it. It would theoretically rise given enough time (viscosity only inhibits fluid flow), but it would take so long that the concrete would start to set first, forming a gel with just enough yield strength to terminate the rise entirely.

That's why concrete must be kept in motion before pouring. If it is allowed to gel (which does not take long), it will not pour.

Answer 2

The weight of the concrete displaced is much higher than the weight of a human body.
Also, it sticks and is difficult to separate. A very high surface tension.
I think that a body would stay flat on the surface, unless you tie a weight to it.

Answer 3

VISCOSITY