# Analysis of Fiber Content and Orientation in Prefabricated Slab Elements Made of UHPFRC: Non-Destructive, Destructive, and CT Scanning Methods

## TL;DR

This study introduces a non-destructive method to analyze fiber content and orientation in concrete slabs, improving quality control in prefabrication.

## Contribution

A novel non-destructive testing method using a coil’s quality factor for fiber analysis in UHPFRC slabs is introduced and validated.

## Key findings

- The coil’s quality factor correlates well with fiber distribution and orientation in UHPFRC slabs.
- The method reliably detects material defects and predicts mechanical properties of the slabs.
- Results were validated using destructive tests and CT scanning, confirming the method’s accuracy.

## Abstract

This study investigates fiber content and orientation in prefabricated slab elements made of ultra-high-performance fiber-reinforced concrete (UHPFRC), using novel non-destructive measurement using a coil’s quality factor, where the coil is put to one side of the specimen only. This allows the analysis of slab specimens of arbitrary size. That then allows an accurate quality control of elements made in the prefabrication industry. This study presents an experimental campaign designed to evaluate the non-destructive principle’s accuracy and practical feasibility. Twenty-five large slab specimens were made in an industrial prefabrication plant using various casting methods to introduce different flow-induced fiber parameters. The slabs were subjected to this non-destructive testing, then destructive bending tests and CT scanning to tie the results together and validate the non-destructive results. The results showed that the coil’s quality factor values correspond well to the distribution (concentration) and orientation of fibers, and the method reliably reveals potential defects of the material and can predict the element’s mechanical properties.