MULTIQUIP MAYCO LS300G, Operation Manual

Page: 18 / 90

PAGE 18 — MAYCO LS300G CONCRETE PUMP • OPERATION MANUAL — REV. #2 (09/09/19)
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 shutdown time becomes too long,
wash out immediately.
If it is necessary to wait 1/2 hour or more for another load
of concrete, to prevent setting of the mix in the system, it
is advisable to consider the following factors (A through D)
affecting the concrete:
„
How old is the concrete?
„
Is there an accelerator, calcium chloride, red label, etc.,
in the concrete?
„ The temperature of the day, 80, 90 degrees?
„ How much system you have out and how stiff was the
mix you were pumping?
Preventing Mix Set-Up After Pump Shutdown
When the pump is stopped for any reason during a pour;
e.g., moving hose, waiting for redi-mix truck, the following
suggestions are offered:
1. Leave the hopper full of concrete at the time of
shutdown. It is important not to let the redi-mix driver
wash too much water into the hopper, as this could
cause separation of the concrete in the hopper.
2. If the shutdown period exceeds 2 to 3 minutes, turn
off the engine so the vibration does not separate the
mix in the hopper which can cause a blockage in the
manifold when the pump is started.
3. If it is necessary to wait 10 minutes or more for another
load of concrete, it is wise to start the pump and pump
6 or 8 strokes every 5 minutes to prevent setting of the
mix in the system. If waiting time is excessive, it would
be wise to wash out the pump and hoses and start over
when the new truck arrives.
GENERAL INFORMATION
4. When pumping stiff mixes and there is waiting time
between redi-mix trucks, it is advisable to add some
water to the last hopper of material and “hand mix” to
ensure an easier start with the following load.
5. When the pumping job requires a stiffer mix, the
following method is suggested for starting: Take a water
hose with a nozzle on it and apply water with a fine
spray to the concrete as it comes down the redi-mix
chute into the pump hopper after the slurry procedure
is completed and you are ready to start pumping.
6. Using this procedure will make it easier to pump
through the clean hose.
7. Hose sizing is very important: We strongly recommend
on harsh mixes, vertical pushes, stiff concrete,
shotcrete, or long pushes, that a 2-1/2" line be used
as far as possible. The advantages of using the 2-1/2"
line are improved pumpability, less pumping pressure
and less wear on the pump.
8. Following the pump operation, proper wash out of all
materials or “build-up” within the pump manifold and
hoses will prevent problems when starting the next job.
9. A thorough inspection of the drive components and
greasing of all bearings after each job will ensure
adequate lubrication and service to the pump which
is normally operating in wet, gritty conditions.
NOTICE
Once the concrete has reached the end of the hose,
DO NOT
apply any more water in this manner as this
procedure is used for starting only.
NOTICE
Over-greasing any bearing on your Mayco pump will not
damage the bearing.