Consolidation and Upgrading of Historic Earth Block Masonry Constructions

Abstract

Earth structures constitute a great part of European Monumental Heritage and are closely related to the wider historic, socioeconomic and environmental aspects of each region. They have been constructed with various materials and techniques which depict the regional constructional traditions, with respect to economy of resources and energy consumption in building. Many techniques of building with earth have been developed, while in South Eastern Europe the mostly encountered type is buildings with earth-blocks. Nowadays there is no policy for their retrofitting, maintenance and upgrading, since the tradition of manufacturing earth masonry has vanished and there is lack of relevant regulations. As a result, earth-block houses have been abandoned and destroyed due to damages from earthquakes, ageing or unsuitable interventions (use of concrete members, cement based mortars) and many historic centers with earth houses have been marginalized and demolished. In this paper, a methodology is presented regarding the analysis of building materials and techniques of historic earth block houses situated in Northern Greece, as well as the design and testing of compatible repair materials for their rehabilitation. A series of laboratory tests have been performed to the historic materials, in order to define their microstructural characteristics and their physico-mechanical and chemical properties. Results have been evaluated and led to the design of compatible repair materials based on earth. A series of soil based grouts were manufactured and tested, while their properties were enhanced by the use of specific additives and admixtures. Experimental results showed that the development of compatible repair materials for the stabilization and restoration of historic earth-block buildings should be based in scientific criteria. This means that proper mortar and grout compositions based on earth could sufficiently fill joints, cracks and lacunae and could therefore lead to the maintenance and upgrading of historic earth block buildings.