Properties of Autogenous Shrinkage in High-Strength Mass Concrete According to Hydration Heat Velocity

2011 ◽  
Vol 311-313 ◽  
pp. 1993-1999
Author(s):  
Kyung Mo Koo ◽  
Gyu Yong Kim ◽  
Hiroyuki Miyauchi ◽  
Yeon Woo Kang

The early-age properties and relationships between hydration heat and autogenous shrinkage in high-strength mass concrete are investigated through analysis of the history curves of hydration heat and autogenous shrinkage. To reduce the hydration heat velocity, micro encapsulated retarder (MR) that could retard cement reaction was applied. In the result of research, the hydration temperature and hydration heat velocity of high-strength mass concrete can be decreased with the reduction of size specimen and use of the retarder. A close relationship could be found between the hydration temperature and autogenous shrinkage; the higher the hydration heat velocity, the higher the autogenous shrinkage velocity and the greater the ultimate autogenous shrinkage.

2011 ◽  
Vol 63 (5) ◽  
pp. 377-389 ◽  
Author(s):  
Gyu-Yong Kim ◽  
Eui-Bae Lee ◽  
Jeong-Soo Nam ◽  
Kyung-Mo Koo

2020 ◽  
Vol 12 (22) ◽  
pp. 9372
Author(s):  
Guang-Zhu Zhang ◽  
Han-Seung Lee ◽  
Xiao-Yong Wang

Ultra-high-strength paste (UHSP) combined with nanomaterials has been extensively studied. However, the research on nano-ZrO2 is limited. In this study, UHSP with various nano-ZrO2 contents is analyzed. The motivation of this study is to clarify the effects of nano-ZrO2 on the hydration products, strength, autogenous shrinkage, and hydration heat of UHSPs. The water-to-binder ratio (w/b) of the specimens is 0.2. The nano-ZrO2 content is 0, 1.5, and 3 wt.%. The strength is measured at the age of 3, 7, and 28 days. The hydration heat is measured from the mixing stage to 3 days. The hydration products are analyzed by X-ray diffraction (XRD) and thermogravimetric analysis (TG). The autogenous shrinkage is measured from the mixing stage for 7 days using a new experimental device. The new experimental device can measure autogenous shrinkage, internal relative humidity, and internal temperature simultaneously. The following conclusions can be drawn based on the experimental studies: (1) Two stages were noticed in the autogenous shrinkage of UHSPs: a variable-temperature stage and a room-temperature stage. The cut-off point of these two stages occurred in roughly 1.5 days. Furthermore, in the room-temperature stage, there was a straight-line relationship between the autogenous shrinkage and internal relative humidity. (2) With the increase of the nano-ZrO2 amount, the compressive strength at 3 days, 7 days, and 4 weeks increased. (3) With the nano-ZrO2 increasing, the flow decreased. (4) With the nano-ZrO2 increasing, the hydration heat increased due to the physical nucleation effect of the nano-ZrO2. Furthermore, the nano-ZrO2 used in this study was chemically inert and did not take part in the cement hydration reaction based on the XRD, differential thermal, and TG data. This paper is of great significance for the development of high-strength cementitious materials doped with nano-ZrO2.


2012 ◽  
Vol 253-255 ◽  
pp. 385-389 ◽  
Author(s):  
Jian Cheng Sun ◽  
Bo Jun Wang ◽  
Wen Zhong Zhao

During the technology development of modem concrete, concrete structure crack (especially early-age crack) becomes more and more serious and has been one of main research directions of civil engineering. This paper aims at the seriousness of concrete structure crack and presents one of main cause is that concrete early-age (especially autogenous shrinkage) become large through the experimental study. autogenous shrinkage are mainly belongs to temperature cracks and desiccation cracks. Analyses the affection of ash and water reducing agent on the hydration heat, under the optimum proportion experiment which aims at reducing he hydration heat of cement. The best program are obtained that double mix with 20% fly ash and 1.5% water reducing agent .Design mortar’s early anti-crack experiment, and study crack-resistance and other mechanical properties based on different ages & different mix proportion. From the experiment, analyses early cracking under the influence of admixtures. The mix proportion of 20% fly ash, 10% slag and 1.2% water reducing agent can minimize the creation of cracks.


2012 ◽  
Vol 12 (4) ◽  
pp. 369-376
Author(s):  
Kyung-Mo Koo ◽  
Gyu-Yong Kim ◽  
Sung-Hyun Hong ◽  
Jeong-Soo Nam ◽  
Kyoung-Su Shin ◽  
...  

2020 ◽  
Vol 256 ◽  
pp. 119223 ◽  
Author(s):  
Dejian Shen ◽  
Chuyuan Wen ◽  
Pengfei Zhu ◽  
Yuhua Wu ◽  
Jiaojiao Yuan

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