In September, 1946, the Research Laboratory prepared and distributed a comprehensive report entitled. "A Summary of Experiments With Air Entrainment in Cement Concrete", which covered field and laboratory experimentation conducted over a period of six years. In February, 1947, specific recommendations based on this report and another dealing with the pressure method of determining air contents resulted in adoption of air entrainment for all concrete pavements and the pressure method as the only accepted method of control.

Among the several projects included in the six years of research were four experimental roads which, of course, are still in service. Although these roads have served their primary purpose from the standpoint of experimentation, there is still much to be gained by periodic inspection of them and careful recording of their progress, especially in view of the fact that five to six year's exposure did not cause appreciable deterioration of the pavements. Accordingly, all four projects were examined during the past summer, and this is a report of their progress as determined by these examinations.

Report Date


Report Number

No. 35

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