A Concrete Failure at Attributed to Aggregate of Low Thermal Coefficient
J. C. Pearson
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Gives the highlights of an investigation to account for a rapid failure of some cast stone steps in the winter of 1937-38. Preliminary studies of the cement, aggregate and concrete gave no clue to the trouble except to show that the aggregate in some way caused rapid failure of the concrete in freezing and thawing tests. Eventually the aggregate was found to have an unusually low thermal coefficient, although resistant to frost action in itself. A number of other low coefficient aggregates were found, and in concrete subjected to freezing and thawing tests, all produced the same type of rapid failure. Such aggregates evidently produced high internal stresses at low temperatures and made the concrete particularly vulnerable to frost action.