Dynamic behaviors of serpentine carbon sequestration foamed concrete under multistage cyclic loading

This study investigates the dynamic behaviors of serpentine carbon sequestration foamed concrete (SC-FC), a novel geotechnical material synthesized through carbonation of reactive MgO, serpentine powder, silty clay, and CO₂ foam. By integrating solid waste utilization with CO₂ mineralization and employing CO₂-based foaming instead of traditional air foaming, SC-FC simultaneously achieves lightweight performance and active carbon sequestration, delivering both environmental and structural benefits. Stress-controlled cyclic loading tests were conducted to evaluate the effects of curing age, confining pressure, and vibration frequency on the hysteretic response, stiffness, and energy dissipation of SC-FC. Test results revealed that SC-FC exhibited nonlinear strain-hardening behavior, with hysteresis loops evolving from linear to spindle-shaped and eventually to concave crescent-shaped as dynamic strain increases. The dynamic elastic modulus ( E d ) increased to a peak value before undergoing nonlinear attenuation, whereas the damping ratio ( D ) decreased initially, then increased nonlinearly and gradually stabilized. Longer curing ages enhanced E d and reduced D beyond the transitional strain (0.03–0.04 %) through increased carbonate densification. Higher confining pressure produced greater E d and a two-phase damping response: positive correlation below the transitional strain and inverse correlation above. Higher vibration frequencies further elevated E d without significantly altering the hysteretic morphology, while reducing D at larger strains. SEM observations confirmed that carbonation products (dypingite and hydromagnesite) improve dynamic stability by enhancing interparticle bonding and filling pore spaces. Orthogonal analysis identified confining pressure as the most influential factor on the maximum dynamic elastic modulus ( E d ₘₐₓ), followed by curing age and vibration frequency. A modified Darendeli’s model was developed to accurately predict E d evolution under multistage cyclic loading. This study provides the systematic evaluation of SC-FC’s dynamic characteristics, providing essential theoretical support for its engineering application. With its excellent dynamic stability, high strength-to-weight ratio, and low carbon footprint, SC-FC represents a promising alternative for subgrades, embankments, and other sustainable geotechnical infrastructure. • Characterized SC-FC dynamic strain-hardening and hysteresis under multistage cyclic loading. • Analyzed effects of curing age, confining pressure, and frequency on dynamic modulus and damping ratio. • Proposed a predictive model to predict dynamic elastic modulus.