Experimental study on the shear performance of brick masonry strengthened with modified oyster shell ash mortar

•Shear tests were carried out on masonry specimens strengthened with modified oyster shell ash mortar.•There is an increase in shear strength for strengthened masonry specimens compared to un-strengthened ones.•Practical equations were developed to estimate shear strength of brick masonry strengthened by mortar replacement. One of the main reasons for the lack of seismic capacity of existing historical masonry buildings in China is that the strength of the lime-clay mortar used in these buildings is insufficient. In this paper, a kind of modified oyster shell ash mortar, which is similar to the ancient mortar used in historical buildings in terms of material composition, is proposed to partially replace the original mortar, so as to strengthening the brick masonry wall. In order to evaluate the strengthening effect of this method, shear tests were carried out on specimens strengthened with modified oyster shell ash mortar. The test results show that the proposed strengthening method has significant effect on improving the shear strength of brick masonry wall with low strength mortar. Based on the test results, the calculation method of shear strength for brick masonry strengthened with partially replaced modified oyster shell mortar is proposed. The calculated results are in good agreement with the experimental ones.