Investigating the High-Temperature Bonding Performance of Refractory Castables with Ribbed Stainless-Steel Bars

Area of Science:

• Materials Science
• Civil Engineering
• Ceramics

Background:

• Refractory materials with calcium aluminate cement (CAC) offer excellent high-temperature mechanical resistance.
• Ultra-high-performance structures require bar reinforcement for fire and explosion protection, making bond performance critical.
• Compressive strength may not accurately predict bond resistance in refractory materials at elevated temperatures.

Purpose of the Study:

• To investigate the bond behavior of ribbed stainless austenitic steel bars in various refractory compositions after high-temperature treatment.
• To determine the relationship between compressive strength and bond resistance under thermal stress.
• To evaluate the suitability of different refractory mixes for reinforced structural applications.

Main Methods:

• Developed and tested four refractory compositions: conventional castable (CC), medium-cement castable (MCC), low-cement castable (LCC), and low-cement bauxite-based castable (LCB).
• Subjected specimens to temperatures of 400 °C, 600 °C, 800 °C, and 1000 °C.
• Conducted mechanical tests, pull-out tests, X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM).

Main Results:

• Bonding resistance, measured by pull-out deformation energy, showed no direct correlation with compressive strength across different refractory compositions and temperatures.
• High-temperature exposure significantly altered material properties, impacting bond performance.
• The study confirmed that compressive strength is not a reliable indicator of bond behavior in these systems under thermal load.

Conclusions:

• The hypothesis that compressive strength does not correlate with bond resistance at high temperatures was supported.
• Findings are crucial for designing reliable reinforced refractory structures for demanding industrial environments.
• Further research into bond mechanisms under thermal cycling is recommended.