The influence of portlandite, calcite, quartz and ettringite inclusions on the multiscale mechanical behaviors of C-S-H matrix

Abstract

C-S-H is the primary binder in cement mixed with additional phases. It is essential to understand how different phases impact cement strength. This study presents an innovative method for preparing a binary system doped with C-S-H and additional phases to study the effects of these phases on the composite's strength. By blending C-S-H with various minerals, we control mineral content precisely. Using multiscale techniques including atomic force microscopy (AFM), hardness and modulus measurements, we quantify the effects of minerals on C-S-H composites. Findings reveal the intrinsic moduli of these phases significantly influence composites' hardness, while cohesion affect compression modulus. Notably, quartz has a higher intrinsic modulus but lower cohesion than C-S-H, resulting in larger hardness but lower compression modulus. Ettringite shows reduced hardness and compression modulus, while calcite and portlandite's effects remain ambiguous due to lower cohesion but larger intrinsic modulus. These insights offer pathways for enhancing cementitious composites' performance.