# Characterizing the Cracking Behavior of Large-Scale Multi-Layered Reinforced Concrete Beams by Acoustic Emission Analysis

## TL;DR

This study uses acoustic emission analysis to understand how large reinforced concrete beams crack under stress, comparing different repair materials and methods.

## Contribution

The study introduces a damage quantification chart based on AE parameters to identify crack stages in multi-layered concrete beams.

## Key findings

- Acoustic emission parameters like number of hits and signal strength effectively detect crack initiation and propagation.
- Rubber particle size and repair layer location significantly influence AE signal characteristics.
- A damage quantification chart was developed to identify first crack and ultimate load stages using H(t) and Sr parameters.

## Abstract

In this study, acoustic emission (AE) analysis was carried out to evaluate and quantify the cracking behavior of large-scale multi-layered reinforced concrete beams under flexural tests. Four normal concrete beams were repaired by adding a layer of crumb rubberized engineered cementitious composites (CRECCs) or powder rubberized engineered cementitious composites (PRECCs), in either the tension or compression zone of the beam. Additional three unrepaired control beams, fully cast with either normal concrete, CRECCs, or PRECCs, were tested for comparison. Flexural tests were performed on all the tested beams in conjunction with AE monitoring until failure. AE raw data obtained from the flexural testing was filtered and then analyzed to detect and assess the cracking behavior of all the tested beams. A variety of AE parameters, including number of hits and cumulative signal strength, were utilized to study the crack propagation throughout the testing. Furthermore, b-value and intensity analyses were implemented and yielded additional parameters called b-value, historic index [H (t)], and severity (Sr). The analysis of the changes in the AE parameters allowed the identification of the first crack in all tested beams. Moreover, varying the rubber particle size (crumb rubber or powder rubber), repair layer location, or AE sensor location showed a significant impact on the number of hits and signal amplitude. Finally, by using the results of the study, it was possible to develop a damage quantification chart that can identify different damage stages (first crack and ultimate load) related to the intensity analysis parameters (H (t) and Sr).