Sustainable strain-hardening magnesium silicate hydrate composite

Binders based on magnesium silicate hydrate (MSH) are promising magnesium-based cements, but they exhibit very high brittleness. Strain-hardening MSH composites (SHMSHCs) were recently explored to address this drawback. However, the previous formulations were found to have high embodied carbon dioxide (ECD) and embodied energy (EE). In this study, a sustainable SHMSHC was developed by adopting an alternative dispersant (for enhanced workability) and cement, as well as reducing the binder content (through aggregate utilisation) and fibre dosage. The selections of the cement and dispersant were based on hydration behaviour, workability and mechanical strength. The SHMSHC development was guided by the micromechanics design theory of strain-hardening cementitious composites. The developed SHMSHC showed superior mechanical performance, with a compressive strength higher than 80 MPa, tensile strain capacity greater than 7% and a tensile strength of about 5 MPa. Furthermore, compared with the previous formulation, the new SHMSHC mix cuts ECD and EE by 25% and 40%, respectively.