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http://dx.doi.org/10.4334/JKCI.2011.23.5.581

Characteristics of Early-Age Restrained Shrinkage and Tensile Creep of Ultra-High Performance Cementitious Composites (UHPCC)  

Yoo, Doo-Yeol (School of Civil, Environmental and Architectural Engineering, Korea University)
Park, Jung-Jun (Structural Engineering & Bridges Research Division, Korea Institute of Construction Technology)
Kim, Sung-Wook (Structural Engineering & Bridges Research Division, Korea Institute of Construction Technology)
Yoon, Young-Soo (School of Civil, Environmental and Architectural Engineering, Korea University)
Publication Information
Journal of the Korea Concrete Institute / v.23, no.5, 2011 , pp. 581-590 More about this Journal
Abstract
Since ultra-high performance cementitious composites (UHPCC) not only represents high early age shrinkage strain due to its low water-to-binder ratio (W/B) and high fineness admixture usage but also reduces the cross section of structure from the higher mechanical properties, it generally has more shrinkage cracks from the restraints of formwork and reinforcing bars. In this study, free and restrained shrinkage experiments were conducted to evaluate the suitability of incorporating both expansive admixture (EA) and shrinkage reducing agent (SRA). The test results indi-cated that approximately 40~44% of free shrinkage strain was decreased. Also, the results showed that 35% and 47% of residual tensile stresses were relieved by synergetic effect of SRA and EA, respectively. Residual tensile stresses from ringtest were relaxed by approximately 61% and 64% of elastic shrinkage stresses due to SRA and EA, respectively, because of the tensile creep effect. Therefore, the creep effect should be considered to precisely estimate the restrained shrinkage behavior of concrete structures. The degree of restraint of UHPCC was approximately in the range of 0.78~0.85. The addition of combined EA and SRA showed minute influence on the degree of restraint. However, the effect decreased when thicker concrete ring was used. Tensile creep strains were measured and compared to the predicted values from 4-parametric prediction model considering time dependent restrained forces.
Keywords
ultra-high-performance cementitious composites; residual stress; creep; shrinkage reducing agent; expansive admixture;
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Times Cited By KSCI : 5  (Citation Analysis)
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