Ceramics-Silikáty 52 (1) 54-60 (2008)

Raman micro-spectroscopy mapping and microstructural and micromechanical study of interfacial transition zone in concrete reinforced by polyethylene terephthalatefibres

V. Machovič, L. Kopecký, J. Němeček, F. Kolář, J. Svítilová, Z. Bittnar, J. Andertová

A new application, the Raman microspectroscopy mapping technique, was successfully used to study of the interfacial transition zone (ITZ) around polyethylene terephtalate (PET) reinforcement in concrete. Waste from PET bottles has been used in form of fibers as a reinforcing element in Portland cement concrete. Raman spectra represent the compositional variation of the cement matrix within the distance range of 5 to 65 µm from the PET fibre. The Raman band at 357 cm^-1 corresponding to the vibrations of Ca–O bond at Ca(OH)₂ was used for quantitative distribution of portlandite within the ITZ area. The most intensive band of portlandite occurs at the distance from 0 to 30 µm from the PET fibre. Raman spectroscopy has been completed with nanoindentation and environmental scanning electron microscopy (ESEM) in combination with microanalysis (EDX), and electron diffraction (EBSD-OIM). The contact zone is characterized by a higher porosity (both air and water pores) and occurrence of newly formed mineral phases - portlandite, hydrocarbonate, ettringite, and lower Ca²⁺ saturated C–S–H gels.

Keywords: Interfacial transition zone, Raman spectroscopy, Microstructure, PET fiber reinforcement