Salt Hazard of Earthen Monuments Induced by Capillary Rise

摘要

Re-distribution and re-crystallization of the soluble salts by capillary water migration in ancient earthen structures results in salt efflorescence which is characterized by granular disaggregation and crumbling.Laboratory capillary water rise tests were conducted on compacted silt soil from ancient Jiaohe Ruins in Xinjiang,China to clarify the responsibility of salts in damage of earthen monuments.Distribution of water contents,pH,electric conductivity and soluble salts of soil liquid after capillary tests illustrated that NaCl accumulation is predominant at the capillary fringe while Na2SO4 at the other capillary front area.Within the capillary rise area along the water migration direction,less soluble,moderately soluble and most soluble salts tend to crystallize out and result in salt crest,salt efflorescence and dark appearance in correspondence.