P. SCHUBERT and H. METZEMACHER Institut fur Bauforschung, R WTH Aachen

The objective of the research work was to determine the flexural strength, parallel and perpendicular to the bed joints, of masonry made from units and mortars in general use in Germany. The test results were to serve as a basis for evaluating the flexural strengths currently Quoted in EC 6, which are essentially based on English test results. Calcium silicate units, perforated clay units, concrete units, lightweight-concrete and autoclaved aerated-concrete units were used in the tests. Strength, perforation and unit size were varied within the kind of units. The mortars employed were laboratory-mixed prescribed mortars of Groups MG Ha and HI according to DIN 1053, together with lightweight and thin-layer mortars used in combination with suitable units. The test procedure for determining the flexural strength of the masonry was essentially the ISO method.
A further aim of the research work was to identify suitable substitutes for the complicated testing procedures used to determine the flexural strength of masonry. For this purpose, the flexural strength of the units and their compressive strength along the longitudinal axis were determined. In addition, unit-mortar bond tensile strength and bond shear strength were determined on 2- or 3-unit specimens.