# Evaluation of ultrasonic signals collected from laboratory concrete specimens: Preprocessing and analysis with coda wave interferometry

## TL;DR

The paper introduces a standardized workflow for analyzing ultrasonic signals in concrete using Coda Wave Interferometry to detect early material damage.

## Contribution

A systematic and reproducible procedure for ultrasonic signal preprocessing and CWI analysis in concrete monitoring is proposed.

## Key findings

- A 400 mm × 100 mm × 100 mm concrete specimen with embedded transducers at 60 kHz is recommended for CWI analysis.
- The workflow ensures consistent and comparable results across studies with reasonable computational cost.
- CWI is effective for detecting early-stage material alterations in concrete structures.

## Abstract

•Standardized preprocessing and Coda Wave Interferometry (CWI) analysis enable low-barrier adoption for new users, ensure comparability between studies, and promote consistent terminology to avoid miscommunication.•Detailed recommendations are provided for a specific concrete specimen size (400 mm × 100 mm × 100 mm) equipped with embedded ultrasonic transducers operating at a center frequency of around 60 kHz, as used in a long-term collaborative research project in Germany.•The proposed workflow offers a systematic and reproducible approach to ultrasonic signal analysis, ensuring consistent results at reasonable computational cost.

Standardized preprocessing and Coda Wave Interferometry (CWI) analysis enable low-barrier adoption for new users, ensure comparability between studies, and promote consistent terminology to avoid miscommunication.

Detailed recommendations are provided for a specific concrete specimen size (400 mm × 100 mm × 100 mm) equipped with embedded ultrasonic transducers operating at a center frequency of around 60 kHz, as used in a long-term collaborative research project in Germany.

The proposed workflow offers a systematic and reproducible approach to ultrasonic signal analysis, ensuring consistent results at reasonable computational cost.

Efficient maintenance of infrastructure relies on monitoring and assessment of its condition. New technologies and methods thereby enable a deeper understanding of the materials used and of the structures built. Coda Wave Interferometry (CWI) is currently explored for continuous monitoring of reinforced concrete structures as well as material testing. This ultrasound-based method is sensitive to even small material alterations and therefore suitable for the detection of initial damage stages. Herein, a step-by-step procedure for the evaluation of ultrasonic signals with CWI methods is presented. The described procedure is proposed for ultrasonic signals collected with embedded ultrasonic transducers with a center frequency of 50 kHz to 70 kHz from prism-shaped concrete specimen with dimensions of 400 mm x 100 mm x 100 mm. The raw ultrasonic signal, preprocessing and CWI analysis are described and influences of parameters within the analysis are discussed. The presented procedure allows systematic and comparable analysis of ultrasonic signals generated with similar conditions and therefore contributes to the application of CWI methods for structural health monitoring and material testing.

Image, graphical abstract