| Title |
Estimation of Strength Development of Super Retarding Concrete Considering Setting Time |
| Authors |
Han Min-Cheol ; Han Cheon-Goo ; Kim Sung-Jung |
| Keywords |
Setting Time ; Maturity ; Apparent Activation Energy ; Super Retarding Agent ; Equivalent Age ; Strength Estimation |
| Abstract |
In this paper, the applicability of maturity approach to the estimation of compressive strength of concrete using super retarding agent(SRA) is described based on apparent activation energy at the final set time, which is derived from Arrhenius function. 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 and it also ranged from 20～40KJ/mol for concrete with SRA. Good agreement between predicted strength and measured strength was obtained based on the estimation of compressive strength applying equivalent age computed from apparent activation energy at final set time. Strength prediction model using equivalent age estimated compressive strength better than that using maturity. However, in case of 0.6% of SRA, strength prediction was not so good as we expected. Hence, it is necessary to conduct additional study to confirm the effect of high dosage of SRA on strength development of concrete. It was found that apparent activation energy derived from setting time could be used to predict the setting time as well as strength estimation of concrete containing SRA successfully. |