Characteristics of Temperature Field of Rammed Earth Wall in Arid Environment

The rammed earth walls were greatly affected by the change of temperature fields in arid environments, particularly the swell-shrink stress caused by gradient variations of the temperature fields was one of the main factors leading to surface weathering of rammed earth sites. While heat conduction, convection, and radiation were the main factors resulting in temperature variations of rammed earth walls. In this study, the thermocouple sensors were embedded in a rammed-earth test wall, to continuously monitor the temperature gradient field of the rammed earth wall from the near-surface area to the interior. The results revealed that the wall was greatly influenced by seasonal temperature fields together with significant changes in daily temperature differences. The top and the surface of the wall were affected by thermal radiation and convection, while the interior and the foundation were affected by heat conduction. The annual temperature difference reached 62.99 degrees C, and the maximum daily temperature difference on the surface of the wall was 24.3 degrees C, which mainly appeared during the spring and autumn seasons. The near-surface thickness of the temperature-sensitive area of the wall was less than 32 cm, within which the temperature varied dramatically at depths of 0-18 cm. The temperature variations at depths of 18-32 cm were somewhat significant with no obvious changes at depths exceeding 32 cm. These trends indicate that the rammed earth wall has an outstanding function of thermal preservation and insulation. This study is expected to be of guidance and reference for multi-field coupling environmental condition setting for surface weathering of rammed earth site bodies, stress and strain caused by temperature field, surface weathering mechanism and strengthening technology as well as the related researches of modern rammed earth building designs.