Synergistic Effects of Mechanical Load and Water Content on Fire Behavior of Compressed Earth Bricks

Earthen construction materials offer environmental benefits and strong thermal, hygric, and mechanical properties, but their fire behavior is not well understood, limiting their use. This study examines how external load and water content affect, simultaneously, the fire behavior of compressed earth bricks. Three types of bricks were tested: unstabilized bricks compacted at 5 and 50 MPa, and cement‐stabilized bricks with 3.5% cement compacted to Proctor level (the compaction necessary to achieve the material's maximum dry density at its optimum water content). These bricks were equalized at 0%, 75%, and 100% relative humidity, then exposed to the time–temperature curve defined in ISO 834‐1 while subjected to loads from 0 to 2.5 MPa. Results showed that at 0% and 100% RH, all materials were thermally stable regardless of load. At 75% RH, SW50 and SWC3.5 became thermally unstable with increased load, at different intensities, while SW5 remained stable. Increased loading affected crack opening/closure, internal pore pressure, and vapor permeation in SW50 and SWC3.5. In contrast, SW5's stability was unaffected by load or crack behavior. Further load‐bearing capacity tests conducted on the thermal stable samples confirmed prior hypotheses about the interrelated thermo‐hydro‐mechanical coupling in the behavior of earthen materials at high temperatures.