Variation in mechanical properties of mortar and masonry

For over a year mortar prisms were tested to validate the mechanical properties of industrially made masonry mortar. The goal was to establish the variation of the tested mortar from the declared property values and the influence on strength of parameters like age, moisture content, and mass per volume. The compressive strength and modulus of rupture were almost twice the values declared by the manufacturer. Tendencies with respect to the relationship between compressive strength and the mentioned test parameters were as expected. Shear and bending tests on masonry made with the tested mortar were also performed and the results compared. Due to the relatively large variation in mechanical properties, no significant relationship between the strength of small scale specimens and larger test walls was found. Variation of properties in one wall was similar to the variation over a number of walls that were made in a one-year period.