Dive summary:

• Extreme cold does not have to cut off concrete pumping on projects if contractors employ some techniques to keep the concrete – and the job – moving.
• One way to add warmth to the line is to use a heat-tolerant hose to channel exhaust from the pumping machinery into the boom to arm the interior, making sure that it can flow through and exit at the hopper so it doesn't create back-pressure on the engine.
• Insulation can be wrapped around the boom to keep heat in, and mixing hot water with both concrete and the slurry in the pipe can keep work moving along.

From the article:

Cold-weather pumping can present a variety of problems as compared to pumping in moderate temperatures. ...