Non-Destructive Multi-Method Assessment of Steel Fiber Orientation in Concrete

Abstract

Integration of fiber reinforcement in high-performance cementitious materials has become widely applied in many fields of construction. One of the most investigated advantages of steel fiber reinforced concrete (SFRC) is the deceleration of crack growth and hence its improved sustainability. Additional benefits are associated with its structural properties, as fibers can significantly increase the ductility and the tensile strength of concrete. In some applications it is even possible to entirely replace the conventional reinforcement, leading to significant logistical and environmental benefits. Fiber reinforcement can, however, have critical disadvantages and even hinder the performance of concrete, since it can induce an anisotropic material behavior of the mixture if the fibers are not appropriately oriented. For a safe use of SFRC in the future, reliable non-destructive testing (NDT) methods need to be identified to assess the fibers’ orientation in hardened concrete. In this study, ultrasonic material testing, electrical impedance testing, and X-ray computed tomography have been investigated for this purpose using specially produced samples with biased or random fiber orientations. We demonstrate the capabilities of each of these NDT techniques for fiber orientation measurements and draw conclusions based on these results about the most promising areas for future research and development.

Non-Destructive Testing in Civil Engineering

“…For the safe use of steel fiber reinforced concrete, non-destructive testing (NDT) methods should be used in order to assess the orientation of the fibers in the hardened concrete. For this purpose, article [7] uses complementary methods of ultrasound, electrical impedance and X-ray computed tomography. The article also demonstrates the capabilities of each of these techniques separately when measuring fiber orientation.…”

Performance Prediction of Anchors in SFRC using Minimally Invasive and Non‐Destructive Techniques

“…Non-destructive testing and evaluation (NDT/NDE), as well as minimally invasive quality evaluation (ND-MIQE) techniques are becoming increasingly popular in the construction industry due to their ability to evaluate the performance of structures and materials without causing damage or disruption to the structure being tested [14]. ND-MIQE techniques are used to assess the quality and integrity of structures by measuring various parameters such as density, sound, temperature, electrical resistivity and moisture content [15].…”

Predicting the Tensile Behaviour of Ultra-High Performance Fibre-Reinforced Concrete from Single-Fibre Pull-Out Tests

“…For the prediction of tensile behaviour, characteristics of fibres intersecting the crack plane are required; therefore, 2D images of cross sections of concrete specimens are frequently studied; however, the fibre orientation can only be roughly determined from such sections [ 31 , 44 , 45 ], and the measurement of the embedded length is not possible at all [ 22 ]. A more accurate characterisation is obtained by quantitative analysis of micro-computed tomography ( CT) images that allow for a reconstruction of the whole fibre system in 3D [ 46 , 47 , 48 ].…”