Abstract
This study investigates the high-temperature performance of lightweight engineered geopolymer composites (LW-EGC) by analyzing the effects of different ceramsite types on thermal stability, compressive strength, and microstructural changes. LW-EGC-M and LW-EGC-C, which incorporate FACM and CC respectively, exhibited higher mass loss, indicating the release of moisture and volatiles. LW-EGC-S, which contains SC, exhibited the lowest mass loss across the entire temperature range. The compressive strength analysis reveals that, although the initial elastic behavior was similar across all aggregates, differences became apparent during the strengthening and yielding phases. At 800 °C, the peak stress of LW-EGC-S decreased significantly, dropping from 20.840 MPa at 20 °C to 6.850 MPa. Microstructural analysis of matrix at elevated temperatures using SEM, XRD, and FT-IR reveals dehydration, shrinkage, and cracking in the matrix, which degrade mechanical performance. However, the melting of PVA fibers in the 200–400 °C range facilitates the release of internal moisture, reducing steam pressure and preventing explosive spalling. While the dehydration of the matrix, the formation of nepheline, and the decomposition of calcite lead to an increase in porosity and a reduction in structural integrity, the fundamental geopolymer network remains stable. This study not only provides new insights into the thermal behavior of lightweight engineered geopolymer composites but also offers a promising approach for enhancing fire resistance in structural applications through the strategic selection of ceramsite types.
Published Version
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