Concrete Aggregates,

To the extent practicable, the selection of an aggregate should be based on knowledge of its significant properties as determined by service record, laboratory tests, and petrographic examination. Service record, when available in sufficient detail, is a most valuable aid in guiding judgment. To be significant, the record should cover structures with concrete proportions and exposures similar to those anticipated for the proposed work. Petrographic or other suitable procedures should be used to determine whether or not the aggregate in the structure and that proposed for use are sufficiently similar to make the service record significant.