Following up to "Mary Fisher" :

Has anyone a rough idea of how much a 2' x 2' x 2" Concrete block would
weigh, please?

24x24x2 = 1152 cu.ins == 18878 cm3

depending on the sort of concrete - assume density of 2.3g/cm3

2.3x18878 = 43419.4cg = 43.4kg ( ~= 95lbs)

More than you'll probably need to know he
http://hypertextbook.com/facts/1999/KatrinaJones.shtml
--
Tim C.