There is a couple of plants out of town that I always have trouble pumping their concrete.  They are good customers so I want to some how resolve this.  Yesterday, it took me 3 hours to do a 1 hour job because I was plugged up all the time.  I was even plugged off a couple of times at the 90 right at the turret.  Is there something I am doing wrong, should I be pumping slower, faster?  My competition pumps concrete from these guys sometimes too, they have the same kind of pump but dont seem too have many problems. 

Also, when you start to prime out, do you hit it hard or slow.  Some guys say they turn it up and and pump fast, others go into it slow.

Usually if it is real rocky or has the appearence of less sand I try to keep it a little on the stiff side,in the past I have found if you get above a 5+ inch slump some mixes will tend seperate and cause you to plur in 90's or reducer. If you can carry a box of powdered laundry soap and stick 2-4 cups in the load and mix it up helps too. If it is a tempermental mix I will use 3/4 volume and roughly 1500 rpm's and sometimes prime out without my tip hose on...Not fool proof but generally works

hi..over here we some times tip the first 1/4  meter out if it looks a bit iffy then try it...other then that if it looks no good at all we just send it back to the plant they soon get the message and seem to sort it out....another tip try washing up liquid to grout up...

We all have at least one company that sends borderline material. When that company is delivering the concrete; the prime is always exciting. Try this out tomorrow and see if it helps.

Get the load to the proper slump. Have the driver mix the drum as fast as it will mix and then STOP THE DRUM - Put it in discharge and bring the crete to the last fin and stop the drum.

It is important that the drum NOT make any slow revs' before discharging.

Begin your prime and discharge material into the hopper.

I have had a good deal of success with this method. I hope it helps some one else. Slow revs' before discharging load are sure to cause you problems when dealing with a marginal mix. 

If i have any problems it's due to the concrete having no air entrainment. Just yesterday pumped 30 yards through a 36 meter and 50 ft of hose. The next truck starts and is separating so bad it stops the agitator. Turns out it is from a different plant, so I stopped that real quick. To get it to pump I had the quality control guy add some air entrainment. Not too much as it messes the finish, but it did pump.

When I go do out of town jobs especially smaller towns, most of my problems are the size of aggergrate, the fact the load is not mixed up long enough,adding water to hard mix sometimes helps,pumping with the volume down will pervent major problems if you do have problems pluggging up, good luck, but if all else fails just ask if they can take some rock off 150 pound or so and add sand, had to do that before and it works.

Thanks for all the suggestions, I will try them out and see what happens.