| Title |
Prediction of Setting Time of Concrete Using Super Retarding Agent with Maturity Method |
| Authors |
Han Min-Cheol ; Han Cheon-Goo |
| Keywords |
setting time ; maturity ; apparent activation energy ; super retarding agent ; equivalent age ; curing temperature |
| Abstract |
In this paper, the applicability of maturity approach to setting time of concrete using super retarding agent (SRA) is discussed under various SRA content and curing temperature. An increase in dosage of SRA and a decrease in curing temperature resulted in retarding the setting time of concrete significantly. Arrhenius function to obtain apparent activation energy(Ea) and Freisleben-Hansen maturity function to achieve the equivalent age were applied in this paper. To obtain apparent activation energy during setting time, modification of Arrhenius function prescribed by ASTM C 1074 was done by substituting ln(kT) for ln(1/t) for Y axis. Apparent activation energy derived from Arrhenius function ranged from 30～35KJ/mol for plain concrete, which was similar to that suggested by Freisleben-Hansen and it also ranged from 20～40KJ/mol for concrete with SRA. Equivalent age was calculated by using Freisleben-Hansen function, which exhibited nearly independence of curing temperature, regradless of with and without SRA. Initial and final setting time of concrete was obtained from the equivalent age calculated with Freisleben-Hansen maturity function for each mixture. Effective quality control method related to the prediction of setting time of concrete using SRA were provided. It was found that Ea during setting period could be successfully estimated by setting time, and maturity function could be used to predict the setting time of concrete with SRA under various curing temperature condition. |