Associate professor, Kuwait University,
Concrete mixes containing set retarding (R) or water reducing and set retarding (WRR) admixtures of different compositions were prepared and then tested by the Proctor penetrometer apparatus to determine the penetration resistance-time relationships. The initial temperature of the different mortar mixes after sieving was 22 ± 1°C. The influence of admixture composition and air temperature (30, 40, and 50°C) on the initial and final times of setting for the different concretes were examined. Admixture dosages used were within the limits recommended by the manufacturers. The results showed that the longest retardation in the times of setting was that achieved by using a phosphate based admixture, followed by that based on lignosulfonate. However, the retardation influence was reduced with an increase in temperature. Linear and nonlinear relationships were found between air temperature and initial and final times of setting for the reference and admixture concretes, respectively.
Paper ID: CCA10038J