Direct tension test of concrete

Abstract

The measured tensile strength of concrete is dependent on the test method used. Compared with indirect methods, the direct tension test method gives results closer to the true tensile strength under pure tension condition. Herein, a new direct tension test method for prismatic specimens that uses bonded steel end plates to apply tension load to the concrete has been developed. A three-dimensional finite element analysis of the test assembly showed that the tensile stresses transmitted to the specimen are very evenly distributed. Approximately 200 concrete prisms with compressive strengths ranging from 10 to 70 MPa were tested using this method. The random distribution of the fracture location indicated that there was no preferred fracture location and no significant end effect. Split cylinder and cube compression tests were also carried out, and the results correlated to those of direct tension test to evaluate their relationship. Lastly, some extra concrete prisms of same sectional size but shorter length had been cast and tested. The dependence of direct tensile strength on specimen length revealed that there might be significant size effect, which should be studied in more details in future research.