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Structural Engineering and Mechanics Volume 49, Number 6, March 25 2014 , pages 763-773 DOI: https://doi.org/10.12989/sem.2014.49.6.763 |
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Autogenous shrinkage of ultra high performance concrete considering early age coefficient of thermal expansion |
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Jung-Jun Park, Doo-Yeol Yoo, Sung-Wook Kim and Young-Soo Yoon
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| Abstract | ||
| The recently developed Ultra High Performance Concrete (UHPC) displays outstanding compressive strength and ductility but is also subjected to very large autogenous shrinkage. In addition, the use of forms and reinforcement to confine this autogenous shrinkage increases the risk of shrinkage cracking. Accordingly, this study adopts a combination of shrinkage reducing admixture and expansive admixture as a solution to reduce the shrinkage of UHPC and estimates its appropriateness by evaluating the compressive and flexural strengths as well as the autogenous shrinkage according to the age. Moreover, the coefficient of thermal expansion known to experience sudden variations at early age is measured in order to evaluate exactly the autogenous shrinkage and the thermal expansion is compensated considering these measurements. The experimental results show that the compressive and flexural strengths decreased slightly at early age when mixing 7.5% of expansive admixture and 1% of shrinkage reducing admixture but that this decrease becomes insignificant after 7 days. The use of expansive admixture tended to premature the setting of UHPC and the start of sudden increase of autogenous shrinkage. Finally, the combined use of shrinkage reducing admixture and expansive admixture appeared to reduce effectively the autogenous shrinkage by about 47% at 15 days. | ||
| Key Words | ||
| ultra high performance concrete; coefficient of thermal expansion; autogenous shrinkage; setting properties; shrinkage reducing admixture; expansive admixture | ||
| Address | ||
| Jung-Jun Park, Sung-Wook Kim : Structural Engineering Research Division, Korea Institute of Construction Technology, Korea Doo-Yeol Yoo, Young-Soo Yoon : School of Civil, Environmental and Architectural Engineering, Korea University, Korea | ||