Material Properties

A Simple Tensile Testing Method for UHP-FRC Based on Double-Punch Test

---

Abstract

Tensile properties are critical parameters of ultra-high-performance fiber-reinforced concrete(UHP-FRC). Current test methods such as the direct tensile test (DTT) and ASTM C1609 requirea complicated test setup and large specimens. These tests are in general time consuming andtypically produce test results with high variability between specimens. A simple, reliable, andreproducible test method in evaluating tensile properties of pre- and post-cracking of UHP-FRC is of paramount importance. In this regard, the double-punch test (DPT) can be a very suitable tensiletesting method for the assessment of mixture quality and tensile behavior of UHP-FRC. The DPTis an indirect tensile test method, and it uses half of the conventional 152.4×304.8 mm (6×12 in.)concrete cylinder as test sample (that is, a 152.4×152.4 mm (6×6 in.) concrete cylinder). Acompression is applied through two steel punches, having 25.4 mm (1 in.) height and 38.1 mm(1.5 in.) diameter, placed at the top and bottom surfaces of the cylinder along its central axis. Thecompressive load generates tensile stresses over diametric planes. A small capacity compressionmachine and a simple arrangement of LVDTs to measure the vertical deformation are the only testsetup requirements, making the test procedure more efficient. The variability in DPT results ismuch smaller because, unlike the results of DTT and ASTM C1609, multiple cracked planesdeveloped upon loading, thereby leading to an averaged mechanical behavior. This paper describesthe DPT testing procedure and compares test results between DTT, ASTM C1609, and DPT. Thispaper also presents an approximate formula for estimating average and maximum crack width using axial deformation and does not require a circumferential extensometer.

Keywords: UHPC, double-punch test (DPT), tensile test, ASTM C1609, direct tensile test, crack width, UHP-FRC

How to Cite:

Tuladhar, S. & Chao, S., (2019) “A Simple Tensile Testing Method for UHP-FRC Based on Double-Punch Test”, International Interactive Symposium on Ultra-High Performance Concrete 2(1). doi: https://doi.org/10.21838/uhpc.9662