Sustainability-driven atomistic model for exploring the mechanical properties of low carbon limestone calcined clay cement (LC³)

Limestone Calcined Clay Cement (LC³) is identified as a promising alternative to cement blends, and it has become an effective way to alleviate the environmental burdens in the cement industry due to its sustainable nature. In this work, we developed the first molecular model to describe the optimized properties of LC³ blend considering its natural sustainability. The proposed model entails the atomistic structures of Calcium-aluminate-silicate-hydrate (C-A-S-H) in LC³, identifying its mechanical properties, tensile deformation behaviors and failure mechanisms. We revealed that the natural atomistic origins contributing to the superior mechanical properties of C-A-S-H in LC³ compared to that in plain cement are: (1) highly polymerized aluminate-silica chain in C-A-S-H enhances its mean chain length and reduces its porosity; and (2) highly activated aluminate monomer strengthens the cross-linked network in C-A-S-H through a series of pozzolanic reactions. Furthermore, we elucidated the failure mechanisms including aluminate-silica chain breakage, nanopore expansion and microcrack evolution of C-A-S-H under tensile loading. Our findings provide atomic insights to uncover the nanoscale structures of C-A-S-H in sustainable LC³, portraying new understandings of their complicated molecular interactions and structural-failure mechanisms and paving ways for the development of sustainable cementitious composites for construction industry with lower environmental impacts.