Conservation and maintenance of the rammed earth of the historic city wall of Pingyao, China

Abstract

One of the remarkable characteristics of the Ancient Pingyao City Wall, which has been listed as Cultural World Heritage Site in 1997, is the internal rammed earth face, behind the exterior brick finishing. Although many consolidation and restoration treatments were carried out in the past decades, parts of the city wall are still in danger to collapse. Laboratory tests show that the loess soil, the main construction material of the Pingyao city wall, is poor in clay. It is not water resistant without any treatment. From 2011 after quality examination the damaged earthen finishing has been restored only with traditional ramming technique. However, based on the visual inspection done in September 2018, protective lime-earth plasters as sacrificial layer to rammed earth finishing may be a technically and financially sustainable solution.