This test method covers the determination of the performance of fiber-reinforced concrete (FRC) using a molded cylinder or drilled core that is placed vertically between the loading platens of a testing machine and compressed by two concentric steel punches on the ends of the specimen. The applied compression results in uniformly distributed, indirect tension along radial planes of the specimen. Test performance is quantified in terms of peak tensile strength and residual tensile strength at a specified post-peak deformation.
Double-punch Test; fiber-reinforced concrete; ultra-high-performance concrete; tensile test
A new test method is proposed for determining the tensile strength and post cracking performance of fiber-reinforced concrete (FRC). The method is based on the double-punch test method (DPTM) of loading a cylindrical specimen with a length-diameter ratio of 1. The DPTM involves loading the specimen in a compression testing machine through 1.5-in. diameter punches at each end. This type of loading results in indirect tensile stresses on radial planes, leading to multiple cracks in the specimen. Vertical movement of the testing machine is measured providing a load-deformation curve from which, the peak tensile strength, and the residual strength at a specified post-peak deformation can be calculated. The advantages of the DPTM over flexural test methods include the following: 1) a truer tensile strength without being computed through back-calculation approach; 2) a larger crack area develops leading to a more averaged performance; 3) simpler apparatus is required making it suitable for routine testing; 4) it allows evaluation of the in-place properties of FRC by testing drilled cores; and 5) the single-operator variability is lower
The title and scope are in draft form and are under development within this ASTM Committee.
Developed by Subcommittee: C09.42
Staff Manager: W Scott Orthey
Date Initiated: 06-28-2020
Technical Contact: Shih-Ho Chao
Ballot: C09.42 (20-02)
Status: Will Reballot Item
Ballot: C09.42 (22-03)
Status: In Balloting