Electrochemical monitoring of alkali-silica reaction using carbon nanomaterial-integrated cementitious sensors

Concrete expanding gel and internal cracking are linked to the alkali-silica reaction (ASR). This interaction between alkali hydroxides and reactive silica particles is one of the primary challenges to the durability of concrete. This work proposes a new electrochemical sensing platform based on cementitious composites doped with highly conductive carbon nanoparticles. This platform is formed from acid-functionalized multi-walled carbon nanotubes (f-MWCNTs) and reduced graphene oxide (rGO). These nanoparticles were evenly disseminated into Type I Portland cement matrices using ultrasonication-assisted mixing and a polycarboxylate ether surfactant. Small loading criteria were 0.05 to 0.1 wt%. Mortar samples with self-sensing cementitious sensors were tested using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and open-circuit voltage after 28 days of accelerated ASR (1 N NaOH at 80 °C). Observing the behavior of mortar samples was used to examine them. Due to the fast ionic conduction and capacitive charge storage of the f-MWCNT/rGO hybrid networks, ASR-induced gel expansion microstructural development was detected with excellent sensitivity. Both silica gel accumulation and pore solution change were revealed by substantial Nyquist plot changes in charge transfer resistance (R_ct) and double-layer capacitance (C_dl). Hysteresis variations in CV curves indicated interfacial deterioration. The post-mortem research examined electrochemical signal patterns using X-ray Diffraction (XRD) and Scanning Electron Microscopy with energy-dispersive X-ray Spectroscopy (SEM-EDS). This investigation verified ASR gel formation and body microcrack propagation. The hybrid nanomaterial sensors maintained their electrical characteristics under high pH and heat stress, proving their endurance and sensing accuracy. Stable sensors demonstrate this. This study shows that improved carbon nanoparticles can allow cementitious systems for in situ, non-destructive ASR monitoring. These scalable solutions can be used in smart infrastructure and predictive maintenance frameworks. • A novel electrochemical sensing platform was developed to detect alkali-silica reaction (ASR) in concrete. • The platform uses acid-functionalized multi-walled carbon nanotubes (f-MWCNTs) and reduced graphene oxide (rGO) as conductive additives. • Nanoparticles were uniformly dispersed in Type I Portland cement using ultrasonication and a polycarboxylate ether surfactant. • Effective sensing performance was achieved with low nanoparticle loading (0.05–0.1 wt%). • Mortar samples were subjected to 28 days of accelerated ASR exposure (1 N NaOH at 80 °C). • Electrochemical techniques including EIS, CV, and open-circuit voltage were used to evaluate sensor performance. • ASR-induced microstructural changes were detected with high sensitivity due to the fast ionic conduction and capacitive behavior of the f-MWCNT/rGO network. • Significant changes in Nyquist plots revealed variations in charge transfer resistance and double-layer capacitance, indicating silica gel accumulation and pore solution alterations. • Hysteresis in CV curves indicated interfacial deterioration associated with ASR. • Post-mortem analysis using XRD and SEM-EDS confirmed the formation of ASR gel and internal microcracks.