C. IGNATAKIS AND K. STYLIANIDES Civil Engineering Department, Aristotle University of Thessaloniki, Greece


The results of an experimental programme concerning the determination of the mechanical characteristics of virgin and strengthened old masonry are presented. Samples of old brick masonry, constructed in 1906, were taken and examined at the Laboratory of R.C. Structures of the Univ. of Thessaloniki. First, specimens of the constituent materials (bricks and mortar) were tested in compression and tension. Then several specimens of virgin masonry were formed and tested in compression (type C specimens), in combined direct shear in joints and compression (type S wallettes) and in combined diagonal and axial compression (type D specimens). Afterwards, another group of type C and D specimens was coated by unilateral or bilateral thin reinforced mortar jacket and tested under the same loading as in the case of the corresponding virgin ones. The main conclusions of the programme are that, as was expected, the constituent materials are rather poor, reveal high scatter and result in a relatively low compressive strength of the virgin masonry; that the strengthening technique used does not increase the compressive strength of the masonry; that increasing the compression in bed joints leads to an increase of local shear strength in joints; that the same “friction” effect is also obvious in specimens tested in combined diagonal and axial compression; and that the strengthening technique used considerably increases the shear strength of the masonry.