Yuki USUI
Shrinkage Cracking Resistance of Concrete that Uses Various Powder Mineral Admixtures
Supervisor : Takumi SHIMOMURA
Mineral admixtures such as fly ash and ground granulated blast-furnace slag are used as effective use for resource. However, in use of admixtures it is necessary to note that shrinkage crack may be generated.
To examine shrinkage cracking resistance of concrete with admixtures, uniaxial restraint shrinkage test were conducted in this study. To investigate how admixtures affect on cracking resistance of concrete, three aspects concerning cracking resistance were examined, which are shrinkage characteristic, stress relaxation characteristic, and cracking criteria.
As results of uniaxial restraint shrinkage test, shrinkage cracking resistance of concrete with any mineral admixtures were lower than that without admixtures. In case of normal strength concrete mix with fly ash or ground granulated blast-furnace slag, the reason of reduction of shrinkage cracking resistance are reduction of strength at early age and reduction of ultimate strain due to mixing of admixtures. In case of high-strength concrete mix with ground granulated blast-furnace slag and silica fume, the reason of reduction of shrinkage cracking resistance is increasing of autogenous shrinkage at early age.
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