An Evaluation of Four Retarding Admixtures in Structural Concrete

Early in 1960, the Construction Division was becoming quite concerned with the growing problem of obtaining satisfactorily smooth reinforced concrete bridge decks. Increasing areas of new decks were not measuring up to requirements when checked with a straight-edge, and rough-riding surfaces were resulting even after corrective grinding. It appeared that, on large pours, perhaps more time for placing and finishing was needed; this was so particularly on hot, windy days when ambient conditions would cause the concrete to set more rapidly. A proposed method of providing more working time was to use retarding admixtures to slow the setting time of the concrete