Microstructural changes and residual properties of fiber reinforced cement composites exposed to elevated temperatures

0377485 - ÚACH 2013 RIV PL eng J - Journal Article
Keppert, M. - Vejmelková, E. - Švarcová, Silvie - Bezdička, Petr - Černý, R.
Microstructural changes and residual properties of fiber reinforced cement composites exposed to elevated temperatures.
Cement Wapno Beton. Roč. 17, č. 2 (2012), s. 77-89. ISSN 1425-8129
Institutional research plan: CEZ:AV0Z40320502
Keywords : fiber reinforced cementcomposites * high temperatures * mineralodical composition * microstructure * residual strength * apparent moisture diffusivity
Subject RIV: JI - Composite Materials
Impact factor: 0.385, year: 2012

The high temperature load causes irreversible changes in the microstructure of cementitious composites resulting in decrease of their mechanical performance and durability. In this paper, the effect of elevated temperatures up to 1000 degrees C on the mineralogical composition and microstructure of four different types of fiber reinforced cement composites is evaluated by means of X-ray diffraction analysis, mercury intrusion porosimetry and nitrogen adsorption porosimetry. The residual properties are characterized by bending strength and apparent moisture diffusivity. Experimental results show that the degradation processes of matrix (gel sintering and aggregates expansion) influence the pore system more significantly than the degradation of thermally unstable fibers. The residual bending strength is positively affected by the thermally stable fibers at least up to 600 degrees C but in a relative sense the strength reduction in composites with this type of fibers is more significant. The apparent moisture diffusivity is found to be exponentially correlated by volume of capillary pores.
Permanent Link: http://hdl.handle.net/11104/0209630