Investigation of the mechanism of high strength development in concrete secondary products by autoclave curing

Research Project

Project/Area Number	16K18132
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Civil engineering materials/Construction/Construction management
Research Institution	Nihon University
Principal Investigator	YAMAGUCHI Shin 日本大学, 生産工学部, 講師 (60582468)
Research Collaborator	ITOH Yoshinari 日本大学, 生産工学部, 教授 UZAWA Masami 日本大学, 生産工学部, 教授
Project Period (FY)	2016-04-01 – 2018-03-31
Project Status	Completed (Fiscal Year 2017)
Budget Amount *help	¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000) Fiscal Year 2017: ¥130,000 (Direct Cost: ¥100,000、Indirect Cost: ¥30,000) Fiscal Year 2016: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Keywords	オートクレーブ養生 / トバモライト / C-S-H / 細孔空隙 / 粉末X線回折 / EPMA / 粉末Ｘ線回折 / Tobermorite / 土木材料
Outline of Final Research Achievements	High strength concrete secondary products are manufactured by applying the autoclaving method which is performed at elevated temperatures and pressures. The purpose of curing at 180℃ and 1 MPa is to activate formation of a hydrate called tobermorite, based on the theory of high strength development employed in manufacturing of autoclaved lightweight aerated concrete (ALC) panels and similar products. The current study revealed that the major occurrence factors of the high strength development would be massive formation of C-S-H and the mixed phase of tobermorite gels before crystallization filling the micropores and densifying the microstructure. This finding suggests a new theoretical concept about high strength development which can lead to a proposal of a low environmental impact autoclaving technique beyond the limit of conventional manufacturing conditions for tobermorite formation.