As of June 2011, Design and Control of Concrete Mixtures 14th Edition is no longer on the PSI list of Reference Materials for the NC Building Contractor Exam. It has been replaced by the 15th Edition , known as Design and Control of Concrete Mitxures 2010, ISBN 0893122173. The bulk of the changes in the newer edition seem to center around light-weight concrete mixtures and the use of lightweight aggregates to produce lightweight concrete mixtures.
In the field and for the NC General Contractor exam the fact that with lightweight concrete some of the more absorptive aggregates may require pre-wetting before use, are good to know. Also with lightweight concrete, finishng operations should be started earlier than normal concrete.
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