As a temporary fix some years ago, I jacked a sheet of 3/4" plywood
against my kitchen lath & plaster ceiling, and poured liquid plaster
onto it from the raised floorboards above. When set I took down the
acro props and it was as solid as a rock. A year later when the
ceiling was taken down as part of a re-furb, it was the hardest part
to come down !

AWEM



Yes, plaster of paris will set fast and is as solid as a rock..and
bonding plaster is close and can be runny and still set too.