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C-30HD — PARTS & OPERATION MANUAL — REV. #4 (03/06/01) — PAGE 15
PUMPING TIPS AND TROUBLE SHOOTING
1. The effects of heat and excessive time on concrete: Hot
concrete, commonly referred to as a hot load, is concrete that
has been in the redi-mix truck in excess of 2 to 3 hours. On a hot
day, this amount of time is even less. A brief explanation of why
heat and time affect concrete: Concrete starts setting by drying
up through a chemical reaction. The catalyst to this reaction is
heat. When pumping a hot load, it is important to remember that
when you have to stop pumping for any reason, add water to
the concrete in the hopper and hand mix and move concrete in
the hose every 5 minutes. If the shut down time becomes too
long, wash out immediately.
2. ADMIXTURES: A remixtures that are designed into the
concrete mix by the redi-mix company or an architectural
engineering company. This section lists common admixtures
and a brief explanation of their function.
A. POZZOLITH 300 R or the equivalent acts as a water
retarder and a lubricant. On a lean mix, long pushes, stiff
mixes, and vertical pushes, Pozzolith 300 R helps
pumpability.
B. MBVR, air entraining, acts as a lubricant.
C. CALCIUM CHLORIDE, commonly referred to as C.C., is
used as an accelerator. When pumping a load with calcium
chloride, it is recommended that you wash out if the waiting
time between delivery trucks becomes too long.
D. SUPER PLASTICIZERS, acts as an accelerator. The
concrete will look very wet after the super plasticizer is
added, but will begin to set up very fast. Wash out
immediately if you do not have a truck waiting. Super
plasticizers are used mainly on commercial jobs.
E. RED LABEL, acts as a water retarder and an accelerator.
Red label will be used mainly on commercial jobs.
F. FLY ASH, is used to help increase the strength of the
concrete and decrease the cement content per yard. This
is one of the most common admixtures used.
NOTE: All admixtures will be shown on the redi-mix concrete
ticket. Before starting the pumping job, ask the driver of the
redi-mix truck to see the concrete ticket and note the
admixtures that exist and take the proper action.
3. When pumping long distance or pumping stiff mixes, you
can expect a drop in volume compared to shorter lines and
wetter mixes due to the change in valve efficiency or cavitation.
4. Leaking manifold seals or hose coupling gaskets which leak
water can cause separation and subsequent jamming at that
point.
C-30HD OPERATING INFORMATION
5. Damaged hoses with internal restrictions can cause
blockages.
6. If a blockage occurs in a hose, “walk the hose” until you find
the point of trouble. The hose will be soft immediately past the
blockage. If this happens at the start, disconnect the hose at
the first coupling past the blockage. Elevate the hose at that
point with the blockage area hanging down.
Note: Use
extreme care! The hose line is under pressure and can
cause serious injury.
Using a hammer, you can pound the
down-stream edge of the packed area until it is free to flow.
Shake all of the sand and gravel out to the end of the hose.
Before reconnecting the hose, start the pump and run a small
amount of concrete out to the end of the hose. This will assure
that all of the separation is out of the hose.
7. The manifold is plugged if the volume at the discharge end
of the hose stops, and the hose is soft. The drive belts will
start to slip and the engine will lugdown.
To clear a plugged manifold,
great care must be taken as a
dangerous condition will exist due to pressure build-up inside
the manifold.
Follow these instructions carefully:
7.1 Stop the pump. Switch off the engine.
7.2 DO NOT open any of the delivery system joint clamps.
7.3 The senior experienced operator must warn all others to
stand at least 20 feet away from the machine and turn their
heads away from the manifold.
7.4 The operator must position himself/herself away from the
hinged side of the manifold.
7.5 Wearing safety glasses, grasp the clamp arm weldment
and carefully pull it open to the primary (safety) position. STOP
count to 20. This will allow the pressure to release.
7.6 After the pressure has been released, open the clamp
arm weldment and swing the hinged discharge cone open.
7.7 Remove blockage with around a 2-foot length of reinforcing
steel rod. Flush the manifolds with water. Make sure the (3” x
2”) reducer is clear of any blockage before closing the
discharge cone.
7.8 After the blockage has been cleared and the pump
manifold has been thoroughly flushed with water, close the
hinged discharged cone and lock into place.
7.9 Before reconnecting hose to the reducer, start the engine
and pump two or three shovels of concrete through the
reducer. This will insure that all the blockage has been cleared.