Research in Japan on Ultra High Performance Fibre Reinforced Cement-based Composites: Two contributions
Event details
| Date | 06.10.2017 |
| Hour | 12:15 › 13:15 |
| Speaker | Yuji Watanabe, Senior Research Engineer, KAJIMA Corporation, Tokyo, Japan, Dr Tohru Makita, Structural Engineer, NEXCO Central, Nagoya, Japan |
| Location | |
| Category | Conferences - Seminars |
Application of UHPFRC with ettringite generation system for precast member and development of cast-in- situ method presented by Yuji Watanabe
Ultra High Performance Fibre Reinforced cement-based Composites (UHPFRC), which typically has a compressive strength of at least 150 MPa and tensile strength of at least 5 MPa, brings a great deal of flexibility and additional value to design and construction, including reduction in weight and increase of long term durability of members, through such excellent material characteristics as high strength, high toughness and high durability. Especially, “AFt-UHPFRC,” an ettringite -generating type UHPFRC, is developed by using Japanese materials and original technology. UHPFRC has been used mainly for precast products manufactured in factories equipped with heat curing facilities in order to utilize its high performance. Recently, mass manufacturing and curing method of precast members assuming the large-scale application have been established in Japan. However, depending on the scale of construction and the conditions, a cast-in-situ method may be more reasonable.
In this seminar, the objectives and design by using precast UHPFRC to prestressed concrete bridge will be introduced with some applications. And reports the results of experiments and construction aiming at establishing a cast-in-situ method for the first time in Japan.
Bio : Yuji Watanabe is senior research engineer of KAJIMA Corporation. He belongs to concrete and construction materials group in Kajima Technical Research Institute (KaTRI) since 2006. He is one of the development members of AFt-UHPFRC (Japanese version of Ultra High Performance Fibre Reinforced cement-based Composites). And he was responsible for the mass production of UHPFRC slab for construction of Tokyo international airport in 2009. He is now engaged in research and development for construction and repair by using high performance concrete.
Expressway renewal project and upgrading of existing bridge decks using UHPFRC presented by Tohru Makita
Central Nippon Expressway Company Limited (NEXCO Central) operates and manages about 2,000 km expressways in the central part of Japan, 40 % of which have been placed in service for more than 40 years and average in-service period of the expressways is now about 30 years. Recent years have seen growing number of damaged and deteriorated bridges in the NEXCO Central’s expressways and the number of damaged and deteriorated bridges will get larger in the coming decades. In view of the situation, extensive renewal project of the expressways was launched in 2015, in which replacement and upgrading of bridge decks are mainly conducted.
In the expressway renewal project, upgrading of concrete bridge decks is planned to be performed by removing about 10cm deep deteriorated top surface of concrete deck and refilling it with fibre reinforced concrete (FRC) made of normal strength concrete and 1.3 vol.-% of steel fibres with length of 30 mm and diameter of 0.5 mm. However, in order to improve the load bearing capacity of bridge decks to satisfy the requirements for increased traffic load, it is often required to increase the deck thickness. By using Ultra High Performance Fibre Reinforced cement-based Composites (UHPFRC) instead of the FRC, increase of the deck thickness is avoided due to its high tensile and compressive strength. Moreover, it is not necessary to apply waterproofing membrane on top surface of bridge decks because UHPFRC has extremely low permeability and functions as protective layer.
Kajima Corporation and NEXCO Central have started a collaborative research project to develop an upgrading method of existing bridge decks using cast-in-situ UHPFRC in 2016. In this presentation, results obtained from the first stage of the research are explained briefly. The UHPFRC mix used in the research is characterised by its matrix densified by ettringite (AFt) formation; thus, it is called “AFt-UHPFRC”. The AFt-UHPFRC was originally developed for fabrication of precast members with thermal curing and hasn’t been applied to existing structures by in-situ casting. In order to understand properties of the AFt-UHPFRC, direct tensile tests and UHPFRC – concrete interfacial bond tests were conducted. The test results were analysed and the necessity to modify the AFt-UHPFRC mix composition to be suitable for upgrading of existing concrete bridge decks was identified.
Bio : Tohru Makita is structural engineer of NEXCO Central since 2002. He obtained his Bachelor’s and Master’s degree in Civil Engineering at Kyoto University and Doctor’s degree in Structural Engineering at EPFL. He is currently engaged in management of design, construction and seismic retrofitting of bridges and development and implementation of new technologies related to bridges.
Ultra High Performance Fibre Reinforced cement-based Composites (UHPFRC), which typically has a compressive strength of at least 150 MPa and tensile strength of at least 5 MPa, brings a great deal of flexibility and additional value to design and construction, including reduction in weight and increase of long term durability of members, through such excellent material characteristics as high strength, high toughness and high durability. Especially, “AFt-UHPFRC,” an ettringite -generating type UHPFRC, is developed by using Japanese materials and original technology. UHPFRC has been used mainly for precast products manufactured in factories equipped with heat curing facilities in order to utilize its high performance. Recently, mass manufacturing and curing method of precast members assuming the large-scale application have been established in Japan. However, depending on the scale of construction and the conditions, a cast-in-situ method may be more reasonable.
In this seminar, the objectives and design by using precast UHPFRC to prestressed concrete bridge will be introduced with some applications. And reports the results of experiments and construction aiming at establishing a cast-in-situ method for the first time in Japan.
Bio : Yuji Watanabe is senior research engineer of KAJIMA Corporation. He belongs to concrete and construction materials group in Kajima Technical Research Institute (KaTRI) since 2006. He is one of the development members of AFt-UHPFRC (Japanese version of Ultra High Performance Fibre Reinforced cement-based Composites). And he was responsible for the mass production of UHPFRC slab for construction of Tokyo international airport in 2009. He is now engaged in research and development for construction and repair by using high performance concrete.
Expressway renewal project and upgrading of existing bridge decks using UHPFRC presented by Tohru Makita
Central Nippon Expressway Company Limited (NEXCO Central) operates and manages about 2,000 km expressways in the central part of Japan, 40 % of which have been placed in service for more than 40 years and average in-service period of the expressways is now about 30 years. Recent years have seen growing number of damaged and deteriorated bridges in the NEXCO Central’s expressways and the number of damaged and deteriorated bridges will get larger in the coming decades. In view of the situation, extensive renewal project of the expressways was launched in 2015, in which replacement and upgrading of bridge decks are mainly conducted.
In the expressway renewal project, upgrading of concrete bridge decks is planned to be performed by removing about 10cm deep deteriorated top surface of concrete deck and refilling it with fibre reinforced concrete (FRC) made of normal strength concrete and 1.3 vol.-% of steel fibres with length of 30 mm and diameter of 0.5 mm. However, in order to improve the load bearing capacity of bridge decks to satisfy the requirements for increased traffic load, it is often required to increase the deck thickness. By using Ultra High Performance Fibre Reinforced cement-based Composites (UHPFRC) instead of the FRC, increase of the deck thickness is avoided due to its high tensile and compressive strength. Moreover, it is not necessary to apply waterproofing membrane on top surface of bridge decks because UHPFRC has extremely low permeability and functions as protective layer.
Kajima Corporation and NEXCO Central have started a collaborative research project to develop an upgrading method of existing bridge decks using cast-in-situ UHPFRC in 2016. In this presentation, results obtained from the first stage of the research are explained briefly. The UHPFRC mix used in the research is characterised by its matrix densified by ettringite (AFt) formation; thus, it is called “AFt-UHPFRC”. The AFt-UHPFRC was originally developed for fabrication of precast members with thermal curing and hasn’t been applied to existing structures by in-situ casting. In order to understand properties of the AFt-UHPFRC, direct tensile tests and UHPFRC – concrete interfacial bond tests were conducted. The test results were analysed and the necessity to modify the AFt-UHPFRC mix composition to be suitable for upgrading of existing concrete bridge decks was identified.
Bio : Tohru Makita is structural engineer of NEXCO Central since 2002. He obtained his Bachelor’s and Master’s degree in Civil Engineering at Kyoto University and Doctor’s degree in Structural Engineering at EPFL. He is currently engaged in management of design, construction and seismic retrofitting of bridges and development and implementation of new technologies related to bridges.
Practical information
- General public
- Free
Organizer
- Prof. Dr Brice Lecampion & Prof. Dr Katrin Beyer
Contact
- Prof. Dr Eugen Brühwiler