# 배합수 냉각방법 및 지연제 사용에 따른 서중 원전콘크리트의 특성

• Lee, Seung-Han (Department of Civil Engineering, Keimyung University) ;
• Jung, Yong-Wook (Advanced Construction Materials Testing Center, Keimyung University) ;
• Jang, Seok-Soo (Advanced Construction Materials Testing Center, Keimyung University) ;
• Yeo, In-Dong (Department of Civil Engineering, Keimyung University) ;
• Choi, Jong-Oh (Advanced Construction Materials Testing Center, Keimyung University)
• 이승한 (계명대학교 토목공학과) ;
• 정용욱 (계명대학교 첨단건설재료실험센터) ;
• 장석수 (계명대학교 첨단건설재료실험센터) ;
• 여인동 (계명대학교 토목공학과) ;
• 최종오 (계명대학교 첨단건설재료실험센터)
• Accepted : 2013.09.06
• Published : 2013.09.30
• 66 3

#### Abstract

In summer and winter, the difference between the temperature during the day and that during the night is high, which leads to various problems during concrete placement, such as cracks and defects in the concrete as well as low durability and strength. Although nuclear power plant concrete is widely used for placement in all seasons, particular attention must be paid to its quality during the summer. Therefore, we evaluated the effects of a cooling method for mixing water, which is a commonly used hot weather precooling method, and the use of a retarder, on the characteristics of Nuclear Power Plant concrete. In the cooling method for mixing water, cold water at 5 was used, with 50% of the water content consisting of ice flakes. The effects of using a retarder were evaluated by reviewing the characteristics of the cement at the unset stage and after hardening. To evaluate the characteristics of the unset cement, we measured the slump, air volumes, setting times, and pressure strengths after hardening. Furthermore, we measured the heat of hydration at different temperatures; the loss of heat was minimized using insulation. Both the slump time and the complete ageing time of the air volume were found to be 120 min at $20^{\circ}C$ and 40 min at $40^{\circ}C$. In the case when the cooling method for mixing water was used and in the case when a retarder was used, the initial and final sets by penetration resistance were delayed, and the delay decreased with increasing air temperature. For the heat of hydration, the cooling method for mixing water not only lowered the maximum temperature but also delayed its attainment. However, the use of a retarder had no effect on the maximum temperature. Moreover, in the early ages (e.g., 3 and 7 days), the pressure strength of the concrete was lower than that of plain cement. However, the strength of 28-day concrete met the standard construction specifications.

#### Keywords

Hot Weather;Nuclear Power Plant Concrete;Quality Control;Retarder;Warter Cooling

#### Acknowledgement

Supported by : 한국에너지기술평가원(KETEP)

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