Development of Mud-Based Grouts for the Consolidation of Earth-Block Masonry

Abstract

Grouting is an old and widely used irreversible technique for consolidating historic masonries. On the other hand, earth structures concern a great part of European monumental heritage, closely related to the wider historic, socio-economic and environmental characteristics of each region. Up to date there is no policy for their retrofitting, maintenance and upgrading, since the tradition of constructing 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), while many villages with earth houses have been marginalized and abandoned. After the analysis of building materials from earth-block structures situated in Northern Greece, three series of mud-based grout trial mixtures were laboratory manufactured based on different types of clay. In each series, the proportion of clay was gradually substituted by other binders (hydrated lime, natural pozzolan, white cement) or combination of them. The fresh (fluidity, penetrability, volume stability) and hardened (dynamic modulus of elasticity, flexural strength, compressive strength) state properties of all mixtures were tested and comparatively evaluated. From the evaluation of the results, it was concluded that the restoration and strengthening of mud-brick structures could be achieved by using compatible and locally available raw materials.