High-temperature damage mechanism and residual bearing capacity evaluation of air lime-stabilized earth after fire

Compacted earthen walls typically remain intact after fire exposure due to their excellent fire resistance, and accurately assessing its residual bearing capacity is crucial. Numerical simulations and laboratory tests were conducted to reveal the temperature field distribution characteristics and performance of compacted earth under fire-exposure. Based on the post-high-temperature (up to 700°C) visual characteristics, ignition loss ( IL ), and analyses of scanning electron microscopy (SEM), methods for determining the maximum fire temperature were proposed. Relationships between temperature and reduction coefficients for unconfined compressive strength ( q u ) and secant modulus ( E 50 ) were established. A preliminary workflow for evaluating the post-fire residual bearing capacity of compacted earth walls was proposed. Combined with high-temperature sintering shrinkage, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) tests, the high-temperature damage mechanisms were elucidated. The color evolution of compacted earth with temperature followed: yellowish-brown, light reddish-brown and reddish-brown. Kaolinite, Ca(OH) 2 and CaCO 3 were identified as the primary minerals undergoing phase transformation at high temperatures. IL exhibited a negative linear correlation with temperature. After exposure to high-temperature, the q u of unstabilized earth increased, whereas the q u of air lime-stabilized earth decreased. The final weight loss rate of air lime-stabilized earth was approximately twice that of unstabilized earth. This research provides critical theoretical foundations and technical support for post-fire safety assessment and restoration of compacted earth walls. • Numerical simulations predict temperature fields in compacted earth under fire. • Methods to determine the maximum fire temperature of compacted earth are proposed. • Heating increases unstabilized earth strength but reduces stabilized earth strength. • Temperature-based reduction coefficients for strength and secant modulus are derived. • Sintering shrinkage, XRD and TGA tests elucidate high-temperature damage mechanisms.