Experimental Comparison Between Two-Course Molded Masonry Specimen and Three-Course Extracted Masonry Specimen in Clay Masonry Structures

This study investigates the relationship between the compressive strength results of two-course molded masonry specimens and three-course masonry specimens extracted from previously constructed masonry, aiming to analyze the reliability of extrapolating laboratory-obtained values to field situations. To achieve this, compression tests were performed on individual hollow clay bricks, laboratory-molded masonry specimens, and masonry specimens extracted from constructed masonry walls, following the prescriptions of NBR 15270-2 [4] and NBR 16868-3 [6]. The results demonstrate that three-course masonry specimens extracted from completed masonry wall exhibit lower characteristic compressive strength compared to two-course molded masonry specimens, highlighting the influence of the height/thickness ratio, construction conditions, and mortar joint continuity between courses on the final strength of the masonry. Additionally, a greater dispersion in the results of extracted masonry specimens was observed, indicating that execution-related factors, such as variations in mortar joint thickness and heterogeneity in the laying process, impact the variability of the tests. The findings of this study may contribute to the evolution of normative criteria and to improving the interpretation of retest results in masonry structures.