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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: A New High Performance Drying Shrinkage-Reducing Admixture
Author(s): M. Masanaga, T. Yamamoto, T. Hirata, and T. Nawa
Publication: Special Publication
Appears on pages(s): 297-308
Keywords: adsorbtion; drying shrinkage; shrinkage-reducing admixture; surface tension
Abstract:Cracking caused by autogeneous and/or drying shrinkage is one of the most important factors that affects to the early deterioration of concrete structures. In this study, the new high performance drying shrinkage-reducing admixture, NSR-1, is introduced. The NSR-1 shows higher drying shrinkage-reducing ability with very low dosage level compared with conventional drying shrinkage-reducing admixtures (DSRA) without effecting other concrete properties. Drying shrinkage-reducing mechanism of conventional DSRA is generally due to reducing the surface tension of water in capillary pores. On the other hand, NSR-1, having hydrophobic groups, adsorbs on cement particles and is able to give hydrophobicity on pore surfaces. As a result, NSR-1 reduces the interfacial tension between pore surfaces and water in these pores, and can reduce drying shrinkage effectively. Drying shrinkage behavior was measured by mortar with W/C of 44%. At 28 days, the shrinkage strain of NSR-1 was 390 × 10-6 at dosage of 0.3 % by mass of cement, and those of conventional DSRA were 380 × 10-6 to 405 × 10-6 at dosage of 2.0% by mass of cement. The NSR-1 showed the same drying shrinkage-reducing effect at a dosage of about one-seventh of the addition amount for the conventional DSRA.
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