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 the initial stiffness, peak tensile strength, residual tensile strength at a specified post-peak deformation, and optionally the average crack width at a specified post-peak deformation.
KeywordsDouble-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 initial specimen stiffness, the peak tensile strength, and the residual strength at a specified post-peak deformation can be calculated. Optionally, the average crack width can be estimated as a function of the deformation. The advantages of the DPTM over flexural test methods include the following: 1) a larger crack area develops leading to a more averaged performance; 2) simpler apparatus is required making it suitable for routine QC testing; 3) it allows evaluation of the in-place properties of FRC by testing drilled cores; and 4) the single-operator variability is lower.
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Draft Under Development