Comments on an indirect tensile test on concrete cylinders

Summary A test which originated in Brazil for determining the tensile strength of concrete involves applying a compressive load to opposite generators of a cylindrical specimen. The specimenfaiL~ in tension along the diametral plane containing the load. Experiments with this teot have shown that: (1) Packing strips of relatively soft material are necessary between the specimen and the platens of the testing machine. Plywood strips ½ in. wide and ⅛ in. thick are satisfactory for the purpose, but the material and dimensions of the strips have little effect, provided they can conform to small irregularities in the surface of the specimen. (2) Cylinders 6 in. in diameter by 6 in. long may be usedfor concrete containing aggregate up to ¾ in. maximum size. Longer specimens may tend to give more uniform results, while smaller specimens may give higher average values. (3) The new test gives results higher than those given by a direct tensile test, but lower than the modulus of rupture of beams. It tends to give m...