Vlatko Bosiljkov ¹

1. Ph.D., assist., Slovenian National Building and Civil Engineering Institute – ZAG, Dimiceva 12, SI-1000 Ljubljana, Slovenia, bosiljko@zag.si

ABSTRACT

Brickwork masonry is a composite, heterogeneous, nonlinear structural material. As with other composite materials, also with masonry the mechanical properties are conditioned with the properties of composite components, their volume ratio and the properties of bond between the bricks and the layers of mortar – joints. Furthermore, since its mechanical properties strongly depend from the orientation of the bed joints and the stress state acting on the joints, the failure modes of in-plane loaded masonry can be attributed either to the failure of each of the aforementioned component or due to their most unfavorable combination.

Following the aforesaid, through investigation of the influence of five different mortar compositions on the mechanical properties of brickwork masonry needed for seismic assessment of masonry structures, an extensive program of testing of mono and biaxially loaded masonry has been carried out. Over 50 specimens were tested by means of compressive, diagonal and shear tests. All masonry specimens were made with solid clay bricks. The basic mortars that were investigated were: cement mortar with the volume ratio of cement to sand = 1:4, cement-lime mortar (cement: lime : sand = 1:1:6) and lime mortar (lime : sand = 1:3). The other two types of mortar were derived through further modifications of the cement-lime mortar with polypropylene fibres (micro-reinforced mortar) and with macro reinforcement of the bed joint by using glass-fibre mesh coated with resin and embedded within the bed joint.

Through phenomenological analysis of the actual failure mechanisms which correspond different testing techniques for in-plane mono and biaxially loaded masonry we have experimentally established the influence of the stiff and soft mortar as well as the micro and macro reinforcement of the masonry on the failure modes. Through tests of in-plane biaxially loaded masonry specimens by means of shear tests of masonry elements we have also

Key words: compressive test, diagonal test, shear, test, failure mechanisms, mortars

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