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Title |
Experimental Study on the Diagonal Shear Performance of Cement Mortar-Plastered Masonry Walls
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DOI |
https://doi.org/10.11112/jksmi.2026.30.4.146 |
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Keywords |
비보강 조적 벽체; 모르타르 미장; 사인장 강도; 전단탄성계수; 하중지지능력 Unreinforced masonry wall; Mortar plaster; Diagonal tension strength; Shear modulus; Load-bearing capacity |
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Abstract |
Unreinforced masonry (URM) walls are widely used in low-rise buildings and non-load-bearing partition walls owing to their simplicity, economy, and short construction time. However, URM walls exhibit inherently brittle behavior and are highly vulnerable to in-plane shear forces during seismic events. In practice, masonry walls are rarely left exposed; mortar plaster is commonly applied to wall surfaces for architectural finish and protection rather than for structural reinforcement. Nevertheless, current masonry design codes typically estimate the diagonal tension strength of URM walls based on unplastered specimens, overlooking the potential structural contribution of plaster finishes commonly present in real buildings. This study experimentally evaluates the diagonal tension strength of masonry walls finished with cement mortar plaster. A total of 24 wall specimens were tested under diagonal compression, with plaster thickness (10 mm and 20 mm), mortar mix ratio (1:3 and 1:5), and plastering configuration (single-faced and double-faced) as the primary test variables. All specimens exhibited a diagonal shear failure mode, and mortar plastering generally improved shear strength and load-bearing capacity. The shear strength and load-bearing capacity increased by up to 35% and 95%, respectively, compared with the control specimens. Furthermore, plaster thickness was found to have a greater influence on shear strength enhancement than the number of plastered faces, while double-faced plastering provided, on average, 29% higher load-bearing capacity than single-faced plastering. These results indicate that plaster thickness, mortar strength, and plastering configuration collectively affect the structural performance of masonry walls, with plaster thickness playing a particularly important role in shear behavior. Double-faced specimens also exhibited a lower shear modulus than single-faced specimens, likely due to microcracking within the thicker plaster layer. The shear modulus-to-elastic modulus ratio (Gm/Em) obtained from the tests was considerably lower than the value recommended by current design codes, suggesting that existing standards may overestimate the stiffness of plastered masonry systems. These findings provide quantitative insight into the structural role of mortar plaster in masonry wall behavior and are expected to serve as a basis for improving the applicability of current masonry design provisions.
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