Characterization of compatible TRM composites for strengthening of earthen materials

Abstract

The high seismic vulnerability of earth constructions has been evidenced by several recent earthquakes that occurred around the World with moderate to high magnitudes, namely Bam 2003, Pisco 2007 and Maule 2010. The seismic risk associated to earth constructions is further amplified by the fact that a great percentage of these constructions is built on regions with important seismic hazard. Thus, the preservation of the immense earthen built heritage and of the life of their inhabitants demands adopting innovative strengthening interventions. However, the success of such solutions requires fulfilling compatibility requirements, while its general use requires adopting affordable materials and low complexity technical solutions. In the last years, textile reinforced mortars (TRM) have been increasingly used to strengthen masonry structures due to their high structural effectiveness and compatibility. In the case of earth constructions, these composite materials are also expected to provide efficient strengthening, though specific component materials should be adopted. This paper presents an experimental program dedicated to the characterization of the composite behavior of two TRM composites proposed for strengthening rammed earth walls. The composites differ on the mesh used, namely a low cost glass fiber mesh and a nylon mesh acquired locally, while the same earth-based mortar was used in both cases. The experimental program involved testing the mortar under compression and composite coupons under tension. In general, the glass TRM presents higher strength and stiffness in tension, while the nylon TRM presents considerably higher deformation capacity. Finally, stress-strain relationships describing the composite behavior are presented for numerical modelling purposes.