A STUDY OF DELAYED FINISHING OF CONCRETE SLABS

THE PERIOD OF ELAPSED TIME BEFORE THE SECOND SCREEDING OPERATION WAS INCREASED TO DETERMINE WHETHER THIS WOULD OVERCOME CERTAIN AIR-ENTRAINED CONCRETE PLACEMENT DIFFICULTIES. THE RESISTANCE OF THE CONCRETE TO FREEZING AND THAWING WAS DETERMINED TO ASCERTAIN WHETHER CONCRETE DURABILITY WAS ADVERSELY AFFECTED BY THE DELAYED FINISHING OPERATIONS. IT WAS INDICATED THAT: (1) FINISHING CAN BE DELAYED LONGER WITH CONCRETES MADE WITH BLENDED CEMENTS (15% NATURAL, 85% PORTLAND) AND AIR ENTRAINING CEMENT THAN WITH STANDARD PORTLAND CEMENT AND VIBRATED BLENDED CEMENT CONCRETE MIXTURE; (2) IN NO CASE DOES SHRINKAGE OR SWELL SERIOUSLY AFFECT FINISHING OR PAVEMENT SMOOTHNESS; (3) FREEZE THAW RESISTANCE IS NOT REDUCED; AND (4) MORE UNIFORM CONCRETE IS OBTAINED WITH AIR ENTRAINING CEMENTS OR CEMENT BLENDS, IN THE AMOUNTS FOUND THROUGH THIS RESEARCH. /AUTHOR/