The water can be heated sufficiently for use in concrete (approximately
150° F.) in kettles on stoves or by steam from a boiler.
A metal smokestack placed horizontally with a fire in one end makes an
efficient heater for the sand and gravel. The materials are piled over
the stack, but not so high that their weight will crush the pipe. Small
quantities of sand and gravel may be heated on top of metal plate with
a fire under it. If a small boiler is available it may be economical to
use steam for heating the sand and gravel. Steam is effective when forced
from nozzles into the piles or circulated through perforated pipes placed
under the material. Covering the piles with canvas or other material will
retain much of the heat.