Adjusting Air Content On-Site

摘要

Q. As the ready mixed concrete producer for a project, our quality assurance staff tested the air content of a load of concrete at the batch plant. The test revealed that the air content was lower than specified, so they added an air-entraining admixture (AEA) to adjust the air content to fall within the range required by the purchaser. At the jobsite, the owner s testing agency determined that the air content was low, but the owner's representative would not allow the batch to be dosed with additional AEA on the basis that the batch ticket showed that there had already been an AEA addition at the plant. The load was therefore accepted with no further additions. We have never experienced this before and believe that additional AEA should have been allowed. Am I correct, or is there a limit on how many times AEA can be added to a batch of concrete?