An experimental program was done at Kansas State University to investigate the possibility of splitting caused by different wire indent patterns used in concrete railroad ties. 5.32-mm-diameter pre-stressing wires with chevron, dot, or spiral indent patterns were tested along with a smooth wire. The wires were tested using a tensioned pullout test setup that was developed to simulate the transfer length bond area interaction between the wire and the concrete. The wires were tensioned to 75% of their ultimate capacity before the concrete specimens were cast around the wire.
Various diameter concrete specimens were tested to determine the amount of cover needed to prevent splitting. The wire was de-tensioned when the concrete had reached 4,500 psi, during which time wire slip and force were measured on each side of the specimen. The spitting behavior found during this testing was used to determine the probability of a wire to cause potential splitting in a concrete railroad tie. Indent geometry data was also compared with this test data to determine a method for predicting the splitting potential based on indent geometry.
