Rehydration of Ultra High Performance Concrete

Abstract:

Ultra High Performance Concrete (UHPC) and High Strength Concrete (USC) are because of the high density of their matrices very susceptible to spalling during fire exposure. By aid of a heat treatment with maximum temperatures of about 450°C a network of capillaries and micro cracks could be formed, which leads like a porous medium to a relief of water vapor already at harmless low pressures and could prevent the materials from spalling. In the framework of the presented study on UHPC some orientating tests have been performed to obtain knowledge concerning alterations of the microstructure during thermal treatment at 150°C, 250°C, 350°C and 450°C and the subsequent storage in air with 100% relative humidity at 20°C as to allow water uptake and rehydration. The tests have shown that by aid of the said treatment generation of a respective porous system was achieved, which remained open for the transport of water vapor at high temperatures, also after water uptake and rehydration of the dehydrated cementitious matrix. However further studies are needed to get information about effects of the treatments on the mechanical properties and the durability of members.

• Periodical: Advanced Materials Research (Volume 897)
• Pages: 275-279
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.897.275
• Online since: February 2014
• Authors: Ulrich Diederichs, Iris Marquardt, Vít Petranek
• Keywords: Dehydration, Desorption, Fire Behavior, High Temperature Behavior, High-Strength Concrete (HSC), Porous Structure, Rehydration, Spalling, Thermal Treatment, Ultra High Performance Concrete, Water Adsorption

References

[1] Hertz, K.: Heat-Induced Explosion of Dense Concretes. Report No. 166, Technical University of Denmark, (1984).

[2] Diederichs, U.; Jumppanen, U. -M.; Penttala, V.: Behaviour of High Strength Concrete at High Temperatures. Report 92, Helsinki University of Technology, Department of Structural Engineering, Espoo (1989).

[3] Diederichs, U.; Jumppanen, U. -M.; Schneider, U.: High Temperature Behavior and Spalling Behavior of High Strength Concrete. Proceedings of the Fourth Weimar Workshop on High Performance Concrete: Material Properties and Design, Hochschule für Architektur und Bauwesen (HAB) Weimar, Germany, 4 – 5 October (1995).

[4] Nishida, A.; Yamazaki, N.; Inoue, H.; Schneider, U.; Diederichs, U.: A Study on the Properties of High Strength Concrete with Short Polypropylene Fibers for Spalling Resistance. International Symposium on Concrete under Severe Conditions, Sapporo, Japan, (1995).

[5] Schneider, U.; Diederichs, U.; Horvath, J.: Verhalten von ultrahochfesten Betonen (UHPC) unter Brandbeanspruchung. Beton- und Stahlbetonbau 98, Heft 7, Verlag Ernst & Sohn, Berlin, (2003).

DOI: 10.1002/best.200301900

[6] Diederichs, U.; Penttala, V.: Experimental Investigations concerning Temperature Behaviour of Ultra High Strength Concrete. Proceedings of the International Workshop Fire Design of Concrete Structures – From Materials Modelling to Structural Performance,. University of Coimbra, Portugal, 8 – 9 November (2007).

[7] Diederichs, U.; Mertzsch, D.; Penttala, V.: Behaviour of Ultra High Performance Concrete at High Temperatures. Proceedings of the International Symposium on Ultra High Performance Concrete. Kassel, Germany, March 5 – 7 (2008).

DOI: 10.1002/best.200790034

[8] Diederichs, U.; Penttala, V.: Structural Alternations and Mass Transfer at Ultra High Performance Concrete at High Temperatures. WCC M8 ECCO MAS 2008 Minisymposium. Venice, 3 – 5 Juli (2008).