# Chloride-Induced Corrosion Performance of ASR-Contaminated Concrete: Coupled Analysis Using Resistance Variation and NT Build 492 Method

## TL;DR

This study shows that ASR in concrete initially speeds up chloride-induced corrosion but may later reduce it by sealing cracks with gels.

## Contribution

The study couples ASR effects with chloride-induced corrosion using resistance and chloride migration tests.

## Key findings

- Reactive beams showed 47–53% lower chloride migration after one year of ASR exposure.
- Crack density and width were higher in reactive beams, but gels formed to refine the pore structure.
- ASR initially accelerated corrosion but reduced chloride migration in the long term.

## Abstract

This study examines how the Alkali–Silica Reaction (ASR) modifies chloride transport and chloride-induced corrosion (CIC) in reinforced concrete beams. Non-reactive and reactive concrete beams were cast with blue metal and dacite aggregates and subjected to a two-stage exposure: (i) alkali-rich immersion at 38 °C to induce ASR, and (ii) impressed-current CIC and NT BUILD 492 chloride migration testing. Microstructural changes were characterized using SEM–EDS and TGA. The reactive specimens developed extensive surface cracking, but after one year of ASR exposure, exhibited 47–53% lower non-steady-state migration coefficients (Dnssm: 7.03–8.02 × 10−12 m2/s) than the non-reactive beam (15.09 × 10−12 m2/s). After two years, Dnssm was reduced by approximately 37–56% (4.78–6.93 vs. 10.92 × 10−12 m2/s). Crack mapping confirmed higher crack density and width in reactive beams, while SEM–EDS and TGA evidenced Ca depletion and the formation of C–(N,K)–S–H gels, which fill cracks and refine the pore structure. Electrical resistance monitoring showed earlier corrosion initiation in ASR-damaged beams but less pronounced resistance loss during the propagation phase. Overall, the results indicate that ASR can initially accelerate corrosion initiation through microcracking and reduced resistivity, but long-term gel deposition can partially seal transport paths and lower chloride migration under the specific conditions of this study.