Title: Evaluation of AASHTO T 397: Standard Method of Test for Uniaxial Tensile Response of Ultra-High-Performance Concrete

Author(s): Sahith Gali and Sri Sritharan

Publication: Materials Journal

Volume: 121

Issue: 1

Appears on pages(s): 105-118

Keywords: AASHTO T 397; direct tensile test; fiber volume; multicracking; tensile behavior; ultra-high-performance concrete (UHPC)

DOI: 10.14359/51739204

Date: 1/1/2024

Abstract:
Ultra-high-performance concrete (UHPC) is a cementitious concrete material known for its sustained post-cracking tensile performance. Various specimen geometries and different test approaches have been used to establish the tensile characteristics of UHPC. Intending to standardize a direct tension test method, this paper independently evaluates a procedure developed by the Federal Highway Administration (FHWA), which has been adopted into AASHTO T 397. To verify the reliability and repeatability of the test method, 216 tensile specimens were cast from three different UHPC types with fiber-volume fractions of 1, 2, and 3% and tested at six laboratories. The measured responses were characterized for different phases of the tensile behavior and analyzed to understand the scatter in the test data. It was found that testing can be executed with a 60 to 70% success rate with carefully prepared samples and some modifications to the proposed test method. The test results show an increase in both the tensile strength and multicracking phase with an increase in fiber-volume fraction, but the crack straining phase depends primarily on the type of UHPC. Using the test data, average and characteristic tensile responses were established, which are intended, respectively, for analysis and design purposes.