Consolidating and penetrating mechanisms of Ca/Mg/Si suspensions in treating earthen heritage surface

• CMS suspension is stable, without concentration gradient or sediment stratification. • A bimodal micro-nano particle distribution of material enhances suspension stability. • “Small particles→nano-products” mechanism enhances suspension transport. • CMS suspension enhances penetration (13-15%) and diffusion (58-69%) in earth matrix. • M-S-H gel improves hardness, water resistance, and durability of earthen heritage. As consolidating materials for the weathered surface of earthen heritage, Ca/Si (CS) and Ca/Mg/Si (CMS) cementing suspensions were prepared to comparatively investigate their particle stability, penetration, reinforcement efficacy, and resistance to weathering. The CMS system exhibits a “bimodal distribution dominated by micro-nano particles” in particle size, contributing to the enhanced stability of its suspension, as evidenced by the minimal concentration gradient change observed during static conditions. Furthermore, the formation of nano-scale spherical M-S-H gel within the CMS system facilitates its penetration into porous matrices. In comparison to CS, CMS suspensions demonstrate a 13∼15% increase in penetration depth and a 58∼69% expansion in diffusion area. Consequently, soil matrices reinforced with CMS suspensions exhibit improved surface hardness, water erosion resistance, and resilience against complex environmental degradation. These findings highlight the CMS system as a promising choice for the conservation and reinforcement of porous earthen structures.