Bond of Steel Bars to Masonry Mortar Joints: Test Results and Analytical Modelling


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In this paper, the preliminary results of a series of pull-out tests conducted on mortar cylinders with embedded bars are presented. The bars are made of high strength stainless steel and are of helical shape to increase mechanical interlocking with the surrounding mortar. Usually, such bars are employed in situ to realize structural repointing in the case of fair-faced masonry walls. To this aim, they are inserted in the mortar bed joints of masonry for providing tensile strength to the walls and with the function of crack stitching. The aim of the present experimental tests is to determine the bond-slip relationship for bars embedded in masonry. Firstly, pull-out tests are conducted on mortar cylinders considering different embedded lengths of the bars. Further tests are on-going on masonry specimens with bars embedded in the mortar joints. An analytical investigation is also carried out for the interpretation of the pull-out test results.



Edited by:

Angelo Di Tommaso, Prof. Cristina Gentilini and Giovanni Castellazzi




M. Maragna et al., "Bond of Steel Bars to Masonry Mortar Joints: Test Results and Analytical Modelling", Key Engineering Materials, Vol. 747, pp. 319-325, 2017

Online since:

July 2017




* - Corresponding Author

[1] E. Franzoni, C. Gentilini, G. Graziani, S. Bandini, Towards the assessment of the shear behaviour of masonry in on-site conditions: A study on dry and salt/water conditioned brick masonry triplets. Construction and Building Materials 65 (2014).


[2] E. Franzoni, C. Gentilini, G. Graziani, S. Bandini, Compressive behaviour of brick masonry triplets in wet and dry conditions. Construction and Building Materials 82 (2015) 45-52.


[3] G. Castellazzi, C. Gentilini, L. Nobile, Seismic vulnerability assessment of a historical church: Limit analysis and nonlinear finite element analysis. Advances in Civil Engineering, (2013), art. no. 517454.


[4] G. Castellazzi, A.M. D'Altri, S. de Miranda, F. Ubertini, An innovative numerical modeling strategy for the structural analysis of historical monumental buildings. Engineering Structures 132 (2017) 229-248.


[5] R.B. Petersen, M.J. Masia, R. Seracino, Bond behavior of near-surface mounted FRP strips bonded to modern clay brick masonry prisms: influence of strip orientation and compression perpendicular to the strip. Journal of Composites for Constructions 13, 3 (2009).


[6] A.I. Osofero, M. Corradi, A. Borri, experimental study of bond strength between titanium bar and lime-based mortar. Journal of Materials in Civil Engineering 27, 6 (2015) 04014182-1, 10.


[7] F. Focacci, A. Nanni, C.E. Bakis, Local bond-slip relationship for FRP reinforcement in concrete, J. Compos. Constr. 4, 1 (2000) 24-31.

[8] L. De Lorenzis, A. Rizzo, A. La Tegola, A modified pull-out test for bond of near-surface mounted FRP rods in concrete, Composites: Part B 33 (2002) 589-603.


[9] E. Garbin, M.R. Valluzzi, C. Modena, Testing and numerical modelling of the structural behaviour of brick masonry strengthened by the bed joints reinforcement technique, 1st WTA-International PhD Symposium - Building Materials and Building Technology for Preservation of the Built Heritage, (2009).


[10] S. Moreira, L.F. Ramos, B. Csikai, P. Bastos, Bond behaviour of twisted stainless steel bars in mortar joints. 9th International Masonry Conference, Guimaraes (2014).

[11] S. Islam., M.A. Hamdy, S. Khaled, A. Hossein, Bond characteristics of straight- and headed-end, ribbed-surface, GFRP bars embedded in high-strength concrete. Construction and Building Materials 83 (2015) 283-298.


[12] R. Eligehausen, E.P. Popov, V.V. Bertero, Local bond stress-slip relationships of deformed bars under generalized excitations, Envir. Engrg. Res. Council, University of California, Berkeley, Calif. (1983).

[13] G. Russo, G. Zingone, F. Romano, Analytical solution for bond-slip of reinforcing bars in R.C. joints, J. Struct. Engrg., ASCE 116, 2 (1990) 336-355.


[14] E. Cosenza, G. Manfredi, R. Realfonzo, Il calcolo della lunghezza di ancoraggio per barre in plastica fibro-rinforzata (FRP), Proceedings 11th congress CTE (1996) 451-461. (in Italian).