Title: MICROSTRUCTURE OF INTERFACIAL TRANSITION ZONE BETWEEN PET FIBRES AND CEMENT PASTE |
Authors: Machovič Vladimír, Lapčák Ladislav, Borecká Lenka, Lhotka Miloslav, Andertová Jana, Kopecký Lubomír and Mišková Linda |
DOI: 10.13168/AGG.2013.0012 |
Journal: Acta Geodynamica et Geomaterialia, Vol. 10, No. 1 (169), Prague 2013 |
Full Text: PDF file (1.5 MB) |
Keywords: fibre reinforced concrete, PET, Raman mapping microspectroscopy |
Abstract: Considerable amount of waste in the form of polyethylene terephthalate (PET) bottles could be utilized in the form of
dispersed microreinforcement in concrete. PET fibres, however, have poor wettability and adhesion to cement paste, which
can be modified by alkaline hydrolysis with sodium hydroxide at elevated temperature. The alkaline treatment was used to
increase fibre surface, which was followed by changes in the structure of the interfacial transition zone (ITZ) and interfacial
bond between fibre and cementitious matrix. Raman microspectroscopy mapping was employed to study microstructural
changes of ITZ within the distance 0 – 250 μm from a PET fibre. The band at 357 cm-1 corresponding to the Ca–O bond
vibration in portlandite was used to determine its distribution. For determination of the relative abundance of ettringite, the
SO4
2- stretching vibration at 987 cm-1 was used. The most intensive bands of portlandite and ettringite were found within the
distance 0 – 50 μm from an unmodified PET fibre. Besides the elevated concentration of these minerals, abundant pores occur
in this region. In the case of alkaline modified PET fibres the ITZ zone was not found. |