19 June 2001
CPM-6: PUMPED CONCRETE
Description: Placing concrete through a pipe or hose using a concrete pump
with attached hopper.
Uses: Often used for placement above water. May be used for underwater
placement in locations with limited accessibility, where the tremie method is not
efficient. The advantages for underwater repairs include:
High quality concrete can be pumped. The mixture must be both workable
and cohesive without blocking the pump.
Workable mixtures containing relatively small coarse aggregate particles
provide an easily placed and dense concrete.
Concrete can be transferred from a barge directly into the forms.
Pumped concrete fills forms from the bottom upwards, displacing the
seawater as more concrete is added.
Restrictions/Cautions: See CPM-5, Tremie Concrete. Also:
a. Carefully control slump of concrete to 15 to 20 cm (6 to 8 inches).
b. Avoid inclines in the pipe whenever possible.
c. If delays are encountered, move concrete about 1 meter (40
inches) every 5 minutes. If concrete becomes stiff due to a long delay, discard
the mix. Do not retemper by adding water.
d. Use rubber hose only for discharge end and short pumping
Preparation: Prepare the repair location in the same manner as cast-in-place
concrete. Also, carefully plan location of pump and routing of pipeline to minimize
moves. The pipeline should be horizontal or vertical whenever possible.
: Not usually required underwater; for above water, see CPM-3: Cast-in-
a. A typical mix proportion is 1:3:1 by weight with a water-cement ratio
of 0.45. Take careful measures to minimize drying shrinkage by selecting a
material mix design with a maximum allowable shortage of 0.05 percent and