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Name:   
Heading: 1.2.1concrete roping, balls in concrete, doing flatwork
Message:
What should a contractor do when they pour a slab and theres a ball in the concrete?

How can a mix plant prevent this from happening?

What causes this to happen?




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Sarah Wittenauer


To complete the pour either break-up or discard the ball, then, if the problem has been a persistent one and not an isolated example after many satisfactory pours,offer a reduced payment and tell the producer you will change suppliers if it happens again.

The problem arises from a failure to mix properly during the initial charging of the mixer.
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Ken Day


Sarah, As a ready mix producer for over 30 years I found two things to cause cement balls. Admixtures hitting the cement during batching or water hitting the cement during batching. Generally speaking you want 80-85% of your water to go in the front of the drum, some of which can be going in with the intial stone but as soon as the cement starts to discharge you want to make sure that all of your head water is in the truck. You ideally want a nice even ribbon feeding of the stone/sand that will pull the cement into the mix. Another thing to look at is the discharge rate assigned to each truck. If an batchman has not been taught properly, they could be loading faster then the truck can take the material and every truck is different. Most batch computers have settings from 1 - 10.

Bob Banka
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Bob Banka
 
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