Investigation of the bond and shrinkage behaviour of TRM strengthening for rammed earth

Abstract

Raw earth constitutes a significant and worldwide spread built heritage, continuously endangered by the occurrence of earthquakes, since earthen structures are acknowledged by their high seismic vulnerability. Thus, the protection of this heritage and of its inhabitants requires adopting efficient and compatible seismic strengthening solutions. The strengthening of rammed earth walls with textile reinforced mortars (TRMs) is a solution being recently investigated, where the incorporation of earth based mortars and low-cost strengthening meshes fulfils compatibility requirements. Nevertheless, the role of the mortar in TRM strengthening is yet insufficiently investigated, namely with respect to the shrinkage and bond behaviours. This paper intends to contribute for filling this gap by presenting an experimental program that included Alcock’s tests, pull-off tests and a novel 2D-shrinkage test based on digital image correlation (DIC) monitoring. As main conclusions, it can be referred that the clay content of earth mortars must be controlled to minimize shrinkage and that the shrinkage of earth mortar coatings is a very fast process.