The nanomechanical properties of non-crosslinked calcium aluminosilicate hydrate: The influences of tetrahedral Al and curing age

Jiaqi Li (1) , Wenxin Zhang (2) , Paula Sanz Camacho (3) , Mathieu Duttine (3) , David Gardner (4) , Carlo Carraro (4) , Roya Maboudian (4) , Thomas Huthwelker (5)

1 AEED - Atmospheric, Earth and Energy Division
2 Caltech Division of Engineering and Applied Science
3 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
4 Department of Chemical and Biomolecular Engineering [Los Angeles]
5 LNS - Laboratory for Neutron Scattering and Imaging [Paul Scherrer Institute]

Calcium aluminosilicate hydrate (C-A-S-H) is the binding phase of both blended cement-based and alkali-activated materials. The intrinsic mechanical properties of non-cross-linked C-A-S-H are important while experimentally unvalidated. Here, the properties are for the first time measured using high-pressure X-ray diffraction. The incompressibility and bulk modulus K0 of C-A-S-Hs are correlated to their nanostructure and stability using nuclear magnetic resonance and X-ray absorption spectroscopies. Al coordination in stable C-A-S-H (Al/Si = 0.1) cured for 546 days is purely tetrahedral (AlIV), while in metastable C-A-S-H (Al/Si = 0.05) cured for only 182 days is both AlIV and pentahedral (AlV). The stable C-A-S-H is stiffer along the a,b,c-axis with higher K0 relative to C-S-H. Short-curing-induced metastable C-A-S-H (Al/Si = 0.05) shows expanded interlayer and softer c-axis, thus lower K0 than C-S-H and the stable C-A-S-H. Our results highlight the stiffening effect of AlIV incorporation and the negative influences of insufficient curing on the nanomechanical properties of non-cross-linked C-A-S-H at Ca/Si = 1.

Domaines: Matériaux

Jiaqi Li, Wenxin Zhang, Paula Sanz Camacho, Mathieu Duttine, David Gardner, et al.. The nanomechanical properties of non-crosslinked calcium aluminosilicate hydrate: The influences of tetrahedral Al and curing age. Cement and Concrete Research, 2022, 159, 106900 (8 p.). ⟨10.1016/j.cemconres.2022.106900⟩. ⟨hal-03727677⟩