Point-Load Test Method for Estimation of In Situ Masonry Mortar Strength

Abstract

The point-load test method (PLTM) commonly used in the geotechnical area is shown in this paper to estimate the compressive strength of in situ masonry mortar. A specially developed portable PLTM instrument was used for mortar sheet testing. The mortar sheets were removed from horizontal masonry joints by drilling cores out, with little preparatory work required. The test mortar sheets were subjected to pressure from two opposing cone heads, and the peak load at the failure of the mortar sheet was recorded. The effect of specimen size and mortar thickness on the point-load strength was examined. A suitable size of mortar sheet was selected for the experiment. The thickness correction method was used to improve the accuracy of the empirical formula. Scattering characteristics were investigated to check the reliability and repeatability of the PLTM results. A strong relationship was noted between the point-load strength of the mortar sheet and cube compressive strength, ranging from M2.5 to M15.0. Contrast tests with other available test methods verified that the PLTM offers an alternative to the masonry mortar compressive test and has high accuracy, requires little preparation, and involves reproducible and quick operation following specimen extraction from joints.