VERMELTFOORT, A.T.1

1) Associate Professor, Eindhoven University of Technology, Structural masonry department, a.t.vermeltfoort@tue.nl

Testing methods for the quality control of bond in masonry are usually described in standard codes of practice. Normally, the average of the 28-day strength of 12 specimens must be equal to a prescribed value. When produced under laboratory conditions mortar may obtain acceptable quality, however, this mortar does not necessarily have the same quality when produced on-site. In practice, target strength is not always achieved because of differences in climatic conditions during sample preparation and storage. It is often assumed that bond only increases after the masonry units have been laid. To investigate the effect of loading on the development of bond strength, a set up was developed that applied a permanent bending load to the specimens. Earlier tests have shown the effect of treatment and storage conditions of test samples. Moisture conditions during preparation and hardening are found to have more influence on bond strength than temperature. Tests reported here, showed that strength decreases when temperature and moisture conditions vary during the hardening process. In addition, a bending load applied to the specimens during that period influenced their strength negatively. When stored under ideal conditions, mortar strength increases, but poor storage conditions can reduce bond strength considerably.

Keywords: Mortar-brick bond, time effects, storage conditions, testing method