A Novel Approach to Quantifying the Failure Modes of Concrete-Epoxy Interface

Area of Science:

• Materials Science
• Civil Engineering
• Forensic Engineering

Background:

• Concrete-Epoxy Interfaces (CEI) in Fiber-Reinforced Polymer (FRP) concrete systems can fail via cohesive failure in concrete (CC), cohesive failure in epoxy (CE), or interfacial failure (IF).
• Current methods for identifying these failure modes rely on subjective human intuition, leading to potential inaccuracies.

Purpose of the Study:

• To develop and validate a novel, objective image processing technique for analyzing CEI fracture surfaces.
• To quantify the failure modes of CEI in FRP concrete systems more accurately.

Main Methods:

• Utilized image processing techniques, including color space segmentation (HVS, CIE L*a*b*, YC_bC_r, RGB), on preprocessed images of CEI fracture surfaces from Three-Point Bending (3PB) experiments.
• Compared the results of the proposed image processing method with a manual validation approach.

Main Results:

• The image processing method successfully evaluated CEI failure modes.
• The CIE L*a*b* color space demonstrated the highest accuracy in evaluating epoxy area and failure modes, with a Root Mean Square Error (RMSE) of 0.10 compared to manual assessment.
• RMSE values for other color spaces were 0.19 (HVS), 0.23 (YC_bC_r), and 0.26 (RGB).

Conclusions:

• The proposed image processing methodology offers an accurate and objective approach to quantifying CEI failure modes.
• This technique is recommended for forensic investigations of FRP concrete system failures to better understand debonding causes.