Mechanical Performance and Microstructural Characterization of PET-Modified Cement Mortars with Metakaolin.
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| Title: | Mechanical Performance and Microstructural Characterization of PET-Modified Cement Mortars with Metakaolin. |
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| Authors: | Kostrzanowska-Siedlarz, Aleksandra1 (AUTHOR), Ponikiewski, Tomasz1,2 (AUTHOR) tomasz.ponikiewski@polsl.pl, Kocot, Agnieszka1 (AUTHOR), Sucharda, Oldrich2 (AUTHOR) |
| Source: | Materials (1996-1944). May2026, Vol. 19 Issue 9, p1682. 13p. |
| Subjects: | Compressive strength, Scanning electron microscopy, Microstructure, Cement composites, Mechanical behavior of materials, Kaolin |
| Abstract: | Highlights: Metakaolin (10 wt%) restores the compressive strength of PET-modified mortars to reference levels. SEM analysis confirms that metakaolin densifies the ITZ and reduces interfacial debonding gaps. High cement replacement (50 wt%) may lead to strength loss, potentially associated with self-desiccation and autogenous shrinkage. Pozzolanic activity of MK improves stress transfer between PET flakes and the cementitious matrix. Matrix refinement is essential to mitigate the hydrophobic effects of recycled plastic aggregates. The incorporation of plastic waste into cement-based materials offers a promising strategy for improving sustainability; however, it is often associated with reduced mechanical performance due to weak interfacial bonding. This study investigates the effect of metakaolin on the interfacial transition zone (ITZ) and mechanical properties of cement mortars modified with polyethylene terephthalate (PET) flakes used for the partial replacement of natural sand. Mortars containing 10 and 50 wt% metakaolin (as cement replacement) and 5 vol.% PET flakes (as sand replacement) were prepared and tested after 28 days of curing. Compressive and flexural strength were evaluated, and microstructural analysis was conducted using scanning electron microscopy (SEM) with a focus on the ITZ. The results indicate that the incorporation of PET flakes leads to a reduction in mechanical properties due to the formation of a porous and weak ITZ. However, the addition of 10 wt% metakaolin significantly improved mechanical properties, enabling PET-modified mortars to achieve strength comparable to the reference mix. SEM observations revealed that metakaolin contributed to the refinement of the microstructure and reduction in ITZ porosity, which enhanced interfacial bonding and improved stress transfer between PET particles and the cement matrix. These findings demonstrate that metakaolin can effectively mitigate the negative effects associated with PET incorporation by improving the microstructural characteristics of the ITZ, thereby enhancing the performance of sustainable cement-based composites. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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