Multiquip LS600P operation manual Effects Of Heat And Excessive Time On Concrete

general information

Fill the hopper with water after making sure that all sand and rock have been removed from manifold. Operate pump at full throttle and the 3/8" diameter hole restriction will create sufficient back pressure to make thorough inspection of all moving parts.

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.

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.

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.

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.

7.Hose sizing is very important: We strongly recommend on harsh mixes, vertical pushes, stiff concrete, shotcrete, 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

Over-greasing any bearing on your Mayco pump will not damage the bearing.

page 18 — MAYCO LS600P CONCRETE PUMP • operation manual — rev. #0 (05/13/13)