Ultra-high performance fiber-reinforced concrete (UHPFRC) is a new type of concrete with improved performances. It is used in a wide range of applications from the most demanding structures such as bridges to architectural buildings. From the viewpoint of sustainability, the treatment of UHPFRC after the service period of structures should be considered.
Ultra-high performance fiber-reinforced concrete (UHPFRC) is a composite material made of cement, a very low water/binder ratio, fine aggregates, additives and fibers. It is usually used for the construction of special structures like bridges or hydraulic structures or architectural buildings. This concrete has been in use since the 1970’s and has a steadily growing market. However, there are only few studies regarding recycling of UHPFRC at its end-of-life.
BRGM and SELFRAG are working together in the European project HISER (Holistic Innovative Solutions for an Efficient Recycling and Recovery of Valuable Raw Materials from Complex Construction and Demolition Waste) funded under H2020 in order to develop a recycling process for UHPFRC waste. The objective is to selectively liberate the steel fibers from the sand/cement paste in order to recycle both fractions in new concrete products with similar mechanical properties than the ones made using raw materials:
- For the steel fibers: they could be used to make new FRC;
- For the fine fraction (i.e. fraction made with the sand and cement paste): it could be used either to make new fiber reinforced concrete or to make new conventional concrete.
A demonstration campaign was performed in June 2017 in the SELFRAG facilities (Switzerland) on 500 kg of UHPFRC sample using a continuous machine called “Pre-Weakening Test-Station” (PWTS). The aims of this campaign were to confirm at pilot scale and in continuous mode the performances of the system and to study the quality of the recovered fractions for their use in concrete manufacturing. This demonstration campaign was carried out successfully and valorization of the recovered fractions in the production of new concretes was investigated by other partners in HISER project.
More information about HISER project: http://www.hiserproject.eu/index.php