This paper presents the results of an experimental programme about the evaluation of the size effect on the compressive behaviour of cylindrical samples of existing masonry. The study focuses on the in-situ coring and experimental testing of core specimens with 150 mm and 90 mm diameter. The 150 mm cylinder, recurrent in minor destructive evaluation of the compressive strength of existing masonry, includes four brick pieces, two mortar beds and one head joint. The 90 mm specimen includes one mortar bed and two segments of brick, and inflicts less damage on the inspected structural member due to its lower invasivity. The experimental research investigates the size effect on four different types of clay brick masonry. The first type was built in the laboratory using historical-like materials. The other three types of masonry belong to structural walls of existing historical buildings. The combination of experimental results from laboratory controlled materials and existing historical members shows that the size of the cylindrical specimen has regular effect on the compressive strength and the Young’s modulus. The consistent relationship found between the compressive strengths of the 150 mm and 90 mm core samples allows the use of the latter specimen for a more respectful inspection of existing structural masonry.

Peer Reviewed