Triaxial compression test study on the influence of single crack on the mechanical properties of reactive powder concrete

To investigate the influence of crack-type defect and confining pressure on the mechanical properties of brittle materials, conventional triaxial compression tests were conducted on five types of prismatic samples with the same size of 41 mm x 70.7 mm x 175 mm at six confining pressures of 0, 5, 10, 20, 40, and 70 MPa, respectively. Among the five types of samples, one is intact, with uniaxial compressive strength of 140 MPa, and the other four are all defective and contain a single prefabricated crack with the length of 10 mm and the inclination angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees, respectively. All samples are made of reactive powder concrete with the same mix proportion. According to the test results, the following conclusions are obtained. (1) For any kind of defective sample and any confining pressure, relative values of the strength deviation that the defective samples deviating from the intact sample are all less than relative values of the strength range (max-min) of the five samples. (2) There exist two critical values p(1) and p(2) of the confining pressure p, the inclination angle of the prefabricated crack has significantly different impact on the compressive strength in the interval of 0 <= p < p(1), p(1) <= p < p(2), and p >= p(2), respectively.