The message
from Tim Hardisty contains these words:

Your slab is approx 60x60x5 cubic centimetres...

About 40Kgs each.
Someone

Empirically, I'd concur with that - lifting one of these is a
struggle, but can be just about done by one (normal!) person.

Someone very kindly gave me 14 of the 3'x2'x2" municipal slabs. I
didn'arf know about that after I'd loaded and unloaded them and carried
them down the garden.

--
Skipweasel
Pay no attention to that man behind the curtain.