Prediction of Compressive Strength of Concrete Using Double-Shear Testing Method

This study presents a partially nondestructive testing (PDT) method, the innovative double-shear test method (DSTM), to improve the accuracy of concrete strength tests in situ and reduce structural damage. This method involves double-shear faces of the concrete core, on which the load is exerted by a specified DSTM apparatus to produce approximately pure shear stress and obtain the shear strength of the concrete core. The DSTM test indicated that some factors (core-drilling direction, specimen diameter, core length, aggregate type, and concrete moisture) do not influence concrete strength, and a strong relationship between DSTM strength and cube compressive strength ranging from 20 to 40 MPa is proposed for testing concrete samples. The reliability and repeatability of the DSTM are greater than those of other in situ test techniques, such as the Schmidt rebound hammer (SRH) and pull-off test method. Features of the visible failure mode of concrete samples certify the correctness of the test results. Test results demonstrated that the DSTM is applicable to in situ tests of concrete compressive strength with much higher accuracy than the core-drilling method, and causes less damage to structures.