There was an episode of MythBusters where they buried a couple pigs in concrete to see what decomposing bodies do in exactly that case. They indeed leave a gross hollow space.
According to the netflix series called High Tides that I watched the rich bury dead bodies in the buildings they build to hide them and Netflix would never lie to me
Can any concrete experts suggest another additive for us to avoid?
Not a concrete expert, but dead bodies. They decompose, can create pockets of pressurised gas, and leave a hollow cavity of no structural strength.
Source: Me. I made it up, but seems plausible.
There was an episode of MythBusters where they buried a couple pigs in concrete to see what decomposing bodies do in exactly that case. They indeed leave a gross hollow space.
According to the netflix series called High Tides that I watched the rich bury dead bodies in the buildings they build to hide them and Netflix would never lie to me