Method for estimation of compressive strength by in-situ cutting mortar sheet

To accurately estimate the compressive strength of in-situ cutting mortar sheets, a partially nondestructive testing (PDT) method, namely the innovative shear testing method (STM) is suggested. The mortar sheet from the horizontal masonry joint was removed by drilling a core. Load was applied through the designated STM apparatus to generate approximately pure shear stress and obtain the shear strength of the mortar sheet. The mortar board to withstand pressure from two opposite cone heads was tested and the peak load was recorded when the mortar board fails. The correctness of the test results can be demonstrated by the visible shear failure mode of the mortar sheets. Scattering characteristics were reviewed to check the reliability and repeatability of STM results. The compressive strength measured by STM is closely related to the cube compressive strength, ranging from M2.0 to M16.0. Comparative testing of STM with other available test methods confirmed that STM offers an alternative to in-situ testing of mortar compressive strength. The accuracy of STM is high, and samples extracted from masonry joints can be directly, repetitively, and quickly tested in-situ.