Test results from four major Florida projects were reviewed for effects of set-retarder use on maintaining slump and strength of concrete held in the mixer for extended time periods in hot weather conditions. Admixtures included ASTM Specification for Chemical Admixtures for Concrete (C 494) Type D water-reducing and retarding and Type G high-range water-reducing and retarding admixtures. Four different cement-admixture combinations were used. Design strengths ranged from 27.6 to 69.0 MPa (4000 to 10 000 psi). The test samples representing the longest delivery times were found to have maintained the specified slump. Their strength levels generally remained at, or exceeded, the average strength of the respective concrete class.