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The use of intentional air entrainment in concrete is now a well-established means for greatly enhancing the ability of concrete to resist the potentially destructive effect of freezing and thawing. Its use should be mandatory when concrete is to be exposed to such an environment, particulary when chemical deicers are being used, as on pavements and bridge decks. A thorough survey of the early development of air entrainment is presented by Gonnerman . The following paragraph from Gonnerman's report is of particular significance: These projects (test roads constructed in 1935–1937) revealed no relationship between surface scaling and composition of the cement, but they did show clearly that portland cement that inadvertently contained “crusher oil” reduced surface scaling as did many of the blends of portland and natural cement that contained tallow added during grinding of the natural cement. Laboratory tests disclosed that the beneficial effect of the crusher oil and tallow was due entirely to the additional air entrapped in the concrete by these air-entraining agents. Other investigators [2–6] came to similar conclusions during the late thirties and early forties.
Manager, Portland Cement Assn., Skokie, Ill.