Lightweight Concrete Durability

Large scale concrete structures has brought about a re-examination of the durability characteristics of structural lightweight aggregate concrete.  Extensive laboratory freeze-thaw testing programs have demonstrated that structural lightweight aggregates, in combination with high quality pastes containing the proper spacing and amounts of air, and permitted a drying period of at least 14 days prior to first freezing, will produce excellent laboratory tested concrete durability. Investigations of a number of in-service lightweight concrete structures in marine environments for up to 60 years verify the laboratory indications of good weathering resistance and suggest the following criteria for future applications:

  1. Use high quality structural lightweight aggregate (both coarse and fine) that has a proven record of durable performance in severe weathering exposure.
  2. Use a minimum cement content of 611 pcy for structures with moderate exposure (building facades, garages) and 748 pcy for concretes with severe exposure (bridge decks, marine environments).
  3. Use air contents suggested by ACI 201 as a minimum starting point, 6% for 3/4", 7.5% for 3/8" aggregate.
  4. Place concretes at reasonable slumps (3"), using best recommended practice for compaction, finishing and curing.

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