The Bond Mechanism in Stone Or Brick to Grout Interfaces

Abstract

An experimental research on the bond between masonry units and grout has been carried out at the National Technical University of Athens. In this study, tension and shear tests on composite substrate/grout specimens were performed. The composite specimens were consisted of two pieces of substrate connected with one grout joint. The substrate was either stone or brick, whereas hydraulic lime or tripartite (lime-pozzolan cement) or cement grouts were used. The experimental results have demonstrated that the developed tensile and shear bond strength of the studied hydraulic lime and tripartite grouts is comparable with those of cement-based grouts. Moreover, the value of the reached bond strength (tensile or shear) is governed mainly by the substrate characteristics and the binding properties of the grouts. It was also found that interfaces subjected to shear exhibited similar behaviour with interfaces within concrete; thus the beneficial effect of normal compressive stress on the interface was confirmed. Finally, the experimental results are used for the formulation of a Mohr-Coulomb criterion for grout to travertine joints in shear-compression and shear-tension. The results of this project clearly confirm the efficiency of grouts with medium or low mechanical properties (tripartite and hydraulic lime grouts) for retrofitting historic masonries.

Uncertainty analysis of the effect of grout injection on the deformation of multi-wythe stone masonry walls

“…Regression analysis on the scatter plots of Figure 8 and the PRCC sensitivity analysis in Figure 9 show the lateral displacements to be most sensitive to the frictional coefficient. This result reinforces the importance of bond development between the stone masonry units and injected grout, which has been the focus of a previous study [57]. Additionally, grout density and compressive strength, and stone modulus were found to have a greater influence on the lateral displacements than the stone's density or Poisson's ratio or the grout's Poisson's ratio.…”

Adhesive Materials for the Conservation Interventions in the Acropolis Monuments

“…As in case of grouts to substrate interfaces presented in and (Vintzileou and Adami 2009) adhesive material to stone interfaces subjected to shear presented the following failure modes (Fig. 4…”

“…In total, sixty six specimens were tested in shear. The shear tests were performed using a shear box device , (Vintzileou and Adami 2009) at a speed of 0.5 mm/min (Fig. 3).…”