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PAGE 10 — C-30HD — PARTS & OPERATION MANUAL — REV. #4 (03/06/01)
GENERAL INFORMATION
The following operating principles and operating suggestions
should prove helpful in the successful operation of your
concrete pump. Your new “small line” concrete pump has been
designed to give you many years of service when operated
properly. A study of the following paragraphs is important to
the successful operation of your new Direct-flo Concrete
Placer.
All concrete pumps require a high level of operator skill and
more frequent service than most of the other construction
equipment. The highly abrasive nature of concrete under
pressure makes it extremely important that expendable wear
components be inspected at regular intervals between jobs
to prevent having to replace these items during a pour.
Experience has proved that inconsistency of batched concrete
mixes and frequent moving of the line requires the operator to
be readily available at all times during pumping to stop the
pump and prevent abuse to the unit which may occur if
unexpected blockages develop.
PUMP MIX GUIDELINES
When ordering concrete, be certain to advise the concrete
supplier that you require a “pump mix”. The Direct-flo manifold
will pump a wide variety of materials, but certain basic
principles must be followed to assure successful pumping, as
follows:
1. Generally speaking, the washed concrete sand and #4
aggregate (pea gravel) should conform to A.S.T.M. standards
in regard to sieve analysis. Sands in some areas are washed
clean of the #100 and #200 mesh fines, which results in
separation and jamming in the manifold while pumping under
pressure. If this condition develops, check with your concrete
suppliers engineers and get their recommendations for
supplementing the lack of the fines. The use of locally accepted
ad-mixs may be required. (For example, Pozzolith, Bentonite
Clay, Plastiments, etc.) When properly prescribed, additives
form the plastic paste sometimes necessary to hold the
cement and aggregate together. NOTE: If jamming conditions
in the pump or hose occur for any reason at all, do not attempt
to use more power to correct the condition. Determine the
cause of jamming, correct it and resume pumping. Trying to
force material through under jammed conditions may result in
damage to the drive system, thus voiding any warranty
services.
2. As a general rule, the use of approximately six sacks of
cement, 70% washed concrete sand and 30% #4 pea gravel
per yard of concrete will result in a pumpable mix. The ideal
nature of sand and rock in certain areas may permit you to
increase the percentage of rock or adjust the mix considerably
to meet the job requirements. When possible, you may
experiment with various mixes in your area to determine the
degree of versatility of the Direct-flo Pump.
3. Uniform gradition of the washed concrete sand and the 1/2”
minus aggregate along with sufficient cement content and
water are important to a successful pump operation.
4. A recommended pumpable mix design would be 70% sand
and 30% aggregate-cement content to be a minimum of 6
sacks. (564 lbs.)
NOTE; Your local sand and rock engineers will give you the
s.s.d. weights of sand and rock required in your local area
which will yield one cubic yard per the above recommendation.
SAMPLE DESIGN MIX
6 1/2 sacks cement (611 lbs.)
1800 lbs. washed concrete sand
1000 lbs. pea gravel
230 lbs. water
5. Test laboratory data has proven in many areas that the
above mix guidelines have produced concrete rated at 3000
psi (28 day test) and upwards of 5000 psi with an increase in
cement.
6. In some areas where the gradation of sand and rock is
ideal and sufficient cement is used along with admixtures, the
Mayco small line concrete pump will handle up to a 50-50
ratio of sand and rock.
7. When the mix is designed for wet gunning applications, it is
normal to increase the cement (up to 7.5 or 8 sacks) and
change the sand to rock ratio to 85% sand and 15% rock.
8. The Mayco concrete pump will valve efficiently when using
cellular-foam concrete mixes upwards of 70 lbs. per cubic foot
wet density. (Below 70 lbs. materials (roof decks) the valving
becomes inefficient.)