Effects of chemical exposure on bond between synthetic fiber and cementitious matrix: Fid-Bau Portal

Effects of chemical exposure on bond between synthetic fiber and cementitious matrix

Kabele, P. / Novak, L. / Nemecek, J. / Kopecky, L.

The present paper lays an experimental background for a micromechanics-based study of the durability of fiber-cement composites exposed to an aggressive environment. It was found that both studied types of chemical exposure - chloride attack and calcium leaching - significantly affect the fiber-matrix interaction. In the former case, the decrease of the chemical bond is to some extent compensated by the improvement of the frictional bond. The latter, however, results in a severe degradation of the bond properties. The measured data will be used in a multiscale framework to predict the mesoscopic mechanical properties of shortfiber ECC composites. However, even without detailed analysis, it appears that the reduction of bond due to leaching is so severe that the composite may loose its ability of multiple cracking and pseudo strain-hardening. The paper also raised several questions which will be addressed in our future research. These include clarification and verification of the microscopic physical and chemical phenomena responsible for the changes of bond properties due to chemical exposition. Even though the main attention was paid to short-fiber composites, the authors believe that, since the governing micromechanisms (e.g. fiber debonding, pullout, rupture) as well as the durability issues are common to fibrous composites in general, the presented approaches and findings might serve the textile concrete community as well.