Resistance of fly ash–Portland cement blends to thermal shock
| Autor: | Toshifumi Sugama, Tatiana Pyatina |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Cement
Thermal shock Materials science Analcime technology industry and agriculture 0211 other engineering and technologies Mineralogy 02 engineering and technology Building and Construction engineering.material 021001 nanoscience & nanotechnology law.invention Portland cement Compressive strength Chemical engineering law Fly ash 021105 building & construction engineering Wairakite Gravimetric analysis General Materials Science 0210 nano-technology |
| Zdroj: | Advances in Cement Research. 28:121-131 |
| ISSN: | 1751-7605 0951-7197 |
| DOI: | 10.1680/adcr.15.00030 |
| Popis: | Thermal-shock resistance of high-content fly ash–Portland cement blends was tested in the following ways. Activated and non-activated blends with 80–90% fly ash F (FAF) were left to set at room temperature, then hydrated for 24 h at 85°C and then for an additional 24 h at 300°C, and tested in five thermal-shock cycles (600°C heat – 25°C water quenching). X-ray diffraction (XRD) and thermal gravimetric analyses, along with calorimetric measurements and scanning electron microscope-energy-dispersive X-ray tests demonstrated that the activated blends form more hydrates after 24 h at 300°C, and achieve a higher short-term compressive strength than do non-activated ones. Sodium meta-silicate and soda-ash engendered the concomitant hydration of ordinary Portland cement (OPC) and class F fly ash (FAF), with the formation of mixed crystalline FAF–OPC hydrates and FAF hydrates, such as garranite, analcime and wairakite, along with the amorphous FAF hydration products. In sodium sulfate-activated and non-activated blends separate OPC (tobermorite) and FAF (amorphous gel) hydrates with no mixed crystalline products formed. The compressive strength of all tested blends decreased by nearly 50% after five thermal-shock test cycles. These changes in the compressive strength were accompanied by a marked decrease in the intensities of XRD patterns of the crystalline hydrates after the thermal shock. There was no significant difference in the performance of the blends with different activators. |
| Databáze: | OpenAIRE |
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