Effect of fly ash cenosphere concrete under elevated temperature

Area of Science:

• Materials Science
• Civil Engineering
• Fire Safety Engineering

Background:

• Concrete structural integrity is compromised by high temperatures during building fires.
• Material properties significantly influence concrete's performance under thermal stress.

Purpose of the Study:

• To evaluate the high-temperature performance of concrete utilizing fly ash cenosphere as fine aggregate and alccofine as a binder.
• To analyze the impact of these replacements on concrete's thermophysical, mechanical, and microstructural properties.

Main Methods:

• Three concrete mix ratios were prepared and exposed to temperatures ranging from 200 to 800°C for 1-3 hours.
• Experimental analyses included thermophysical assessments, weight loss, pore structure analysis, residual compressive strength, and failure mode observation.
• Chemical deterioration was examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy.

Main Results:

• Residual compressive strength decreased significantly in control concrete (CC) but showed less reduction in fly ash cenosphere and alccofine modified concrete (FACC and FACCAF).
• FACC and FACCAF mixes exhibited reduced strength loss (18.13–34.33% and 17.98–29.64%, respectively) compared to CC (53.18–72.50%) after thermal exposure.
• Microstructural analysis indicated that the addition of fly ash cenosphere and alccofine improved thermal resistance by densifying the concrete matrix and pore structure.

Conclusions:

• The incorporation of fly ash cenosphere and alccofine enhances concrete's resistance to elevated temperatures.
• These materials contribute to thermal stability by managing thermal energy within the concrete matrix and refining its pore structure.