Smooth surface of Self-Compacting Concrete with independent stable fine entrained air

Research Project

Project/Area Number	17K14710
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Civil engineering materials/Construction/Construction management
Research Institution	Kochi University of Technology
Principal Investigator	Attachaiyawuth Anuwat 高知工科大学, システム工学群, 客員研究員 (40770938)
Project Period (FY)	2017-04-01 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000) Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords	自己充填コンクリート / 表面気泡 / 連行空気泡 / 増粘剤 / 隠れ気泡 / 新型増粘剤 / 微細気泡 / 空気量の経時変化 / 空気泡 / 微細空気泡 / 分離低減剤 / self-compacting concrete / entrained air / surface of concrete / surface air bubble
Outline of Final Research Achievements	It was hypothesized that the air bubbles remaining within concrete moved and floated upwards to become surface air bubbles on the boundary surface with the formwork after hardening. A mortar test was established for self-compacting concrete to prevent the occurrence of residual air bubbles on the surface after hardening by reducing the movement and flotation of air bubbles. The relationship between the air content reduction of fresh mortar with time and the surface air bubbles of the hardened mortar was investigated. There was a correlation between the air content reduction 2 hours after mixing and the total area of air bubbles of diameter 500 micro meters or larger remaining on the surface when the water cement ratio is constant and viscosity modification additive is not used. However, surface air bubbles did not occur regardless of the air content reduction with time in the test specimens where the water cement ratio was reduced and viscosity modifying additive was added.
Academic Significance and Societal Importance of the Research Achievements	単位セメント量の少ない，安価で経済的な自己充填コンクリート成立のために連行されるようになった微細気泡がフレッシュコンクリート中では移動しにくい性質を活かした，コンクリート硬化後の表面気泡抑制技術を実証することが出来た。フレッシュコンクリートの変形の際の固体粒子間摩擦緩和に有効な微細気泡が表面気泡の防止にも有効であることから，施工の合理化・省力化に貢献する自己充填性と美観を両立させた，社会貢献度の高い技術である。