UFC 4-150-07
19 June 2001
CPM-5: TREMIE CONCRETE
Description: The primary method of placing concrete underwater when gravity
flow is adequate. The tremie, a steel tube or rigid hose, runs from a hopper for
filling its upper end into the form and is moved vertically as the concrete is
placed.
Uses: All underwater pours at easily accessible locations that require a quantity
of concrete to warrant the equipment set-up.
Restrictions/Cautions:
a. Do not use an aluminum alloy tremie to avoid reaction with the
concrete mix.
b. Location, and space in the form, must be accessible for positioning
and moving the tremie vertically and horizontally.
c. Slump of concrete mix must be carefully controlled within 15 to 20
cm (6 to 8 inches). Too wet a mix may segregate and too dry a mix will not flow
properly in the form.
d. If practicable, place concrete when water temperature is above
10C (50).
Preparation: Prepare the repair location in the same manner as cast-in-place
concrete. Also, ensure that the tremie pipe is heavy enough to be negatively
buoyant, and that the joints in the tremie are well gasketed and sealed. The
diameter of the tremie should be at least eight times the largest size aggregate
used.
Concrete Mix:
a. A typical mix proportion for cement, sand, aggregate, is 1:1.7:2.4 by
weight with a water-cement ratio of 0.45.
b. Use air-entraining and water-reducing plasticizer admixtures as
required for the underwater repair. Admixtures conforming to ASTM C 494 are
acceptable.
c. Use a mineral admixture of pozzolan in thick sections to control
heat buildup. This will reduce amount of cement in the mix.
Placement:
7-15
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