저열 시멘트 콘크리트의 건조수축 및 크리프 거동 평가 = Evaluation of Shrinkage and Creep Behavior of Low-Heat Cement Concrete

국문 초록 (Abstract)

개발된 저열 시멘트 콘크리트의 장기거동 특성인 비구속 건조수축과 크리프가 양생온도를 주요 변수로 측정하였다. 저열 콘크리트의 목표 압축강도인 42MPa를 고려하여 양생온도 5, 20, $40^{\circ}C$에서 물-결합재비는 각각 27.5, 30, 32.5%를 선택하였다. 콘크리트의 건조수축 변형률은 양생온도가 낮을수록 모세관 수 및 겔 공극수의 증발지연으로 인해 감소하는 경향을 보였다. 반면 크리프 변형률은 전이 온도 크리프의 발생으로 인하여 초기 양생온도가 낮은 실험체에서 높았다. 콘크리트 구조설계기준(KCI) 예측모델은 ACI 209 예측모델에 비해 실험결과와 잘 일치하였지만 개발된 저열 시멘트에 대한 보정계수의 제안이 필요하였다.

다국어 초록 (Multilingual Abstract)

This study examined the long-term inelastic characteristics, including unrestrained shrinkage and creep, of low-heat cement concrete under different ambient curing temperatures. To achieve the designed compressive strength of 42MPa, water-to-binder ratios were selected to be 27.5, 30, and 32.5% for curing temperatures of 5, 20, and $40^{\circ}C$, respectively. Test results showed that the shrinkage strains of concrete mixtures tended to decrease with the decrease in curing temperature because of the delayed evaporation of internal capillary and gel waters. Meanwhile, creep strains were higher in concrete specimens under lower curing temperature due to the occurrence of the transition temperature creep. The design models of KCI provision gave better accuracy in comparison with test results than those of ACI 209, although a correction factor for low-heat cement needs to be established in the KCI provision.

참고문헌 (Reference)

1 Aashay A, "Ternary Blends Containing Slag and Interground/Blended Limestone: Hydration, Strength, and Pore Structure" 102 (102): 113-124, 2016

2 Menéndez G, "Strength Development of Ternary Blended Cement with Limestone Filler and Blast-Furnace Slag" 25 (25): 57-63, 2003

3 Korea Concrete Institute, "New Concrete Engineering" Kimoondang Publishing Company 932-, 2001

4 Korea Concrete Institute, "Mass Concrete Thermal Crack Control" Kimoondang Publishing Company 166-, 2010

5 "KSA. Korea Industrial Standard"

6 Tang SW, "Hydration Process of Fly Ash Blended Cement Pastes by Impedance Measurement" 113 (113): 939-950, 2016

7 Kim SJ, "Hydration Characteristics of Low-Heat Cement Substitute by Fly Ash and Limestone Powder" 8 (8): 5847-5861, 2015

8 Gao PW, "Effects of Fly Ash on the Properties of Environmentally Friendly Dam Concrete" 86 (86): 1208-1211, 2007

9 Langan BW, "Effect of Silica Fume and Fly Ash on Heat of Hydration of Portland Cement" 32 (32): 1045-1051, 2002

10 Korea Concrete Institute, "Concrete Structure Code" Kimoondang Publishing Company 342-, 2012

11 "ASTM C 150/C150M-16. Standard Specification for Portland Cement"

12 "ACI Committee 209, Prediction of Creep, Shrinkage, and Temperature Effects in Concrete Structures: Reapproved 2008(209R-92)"

13 "ACI Committee 207, Guide to Mass Concrete (ACI 207.1R-05)"