John Schmitt wrote:
Depending to some extent on the height of the pour. A few years back
in New York I saw a third storey pour being made. The mixer trucks
were queued up in a line. Once the one at the pump emptied, it would
drive out of the queue and the next one would just reverse up and
start discharging. I was impressed.

Back in the mid 1970's I used to sell the hoses for concrete pumps, 6" bore
IIRC. In them days Putzmeister's slogan was " a metre a minute". Just
checked their web site and things have moved on a bit. Biggest beastie can
chuck out 160 cu/m an hour!!

Dave