Work

Thermal and carbonation resistance of tunnel concrete: Experimental evaluation and hybrid ANN–GPR modeling under fire–CO₂ exposure

Year: 2025

Type: article

Abstract: This study investigates the combined effects of high-temperature fire exposure and CO₂-induced carbonation on the mechanical and durability performance of concrete used in urban tunnel infrastructure. Experimental results indicated up to a 43.5 % reduction in compressive strength after exposure to 1000 °C for 180 min, primarily due to thermal degradation and porosity increase. Carbonation depth increased by 24.8 % under the same conditions, attributed to microcracking and enhanced CO₂ ingress. Microstructural characterization using XRD revealed decomposition of Ca(OH)₂ and partial formation of CaCO₃, confirming mineralogical deterioration. Ultrasonic pulse velocity (UPV) measurements showed strong correlation with both strength loss and carbonation depth, supporting UPV as a reliable non-destructive evaluation method. A hybrid machine learning model combining artificial neural networks (ANN) and Gaussian process regression (GPR) was developed to predict residual compressive strength and carbonation depth based on UPV and exposure parameters. The model achieved high predictive accuracy (R² > 0.93), offering a robust, data-driven framework for rapid structural assessment. These findings provide valuable insights into post-fire durability evaluation and support effective maintenance strategies in tunnel engineering.

Source: Case Studies in Construction Materials

DOI: 10.1016/j.cscm.2025.e05076

Authors: Amirhossein Fatemi, Ahmad Ganjali, Reza Babaei Semiromi, Pejman Aminian

Institution: Islamic Azad University, Shahrood

Language: English

Topic: Fire effects on concrete materials

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Industry, innovation and infrastructure, Climate action, Sustainable cities and communities

Open Access status: gold

Estimated APC paid: $2,660