Plastic deformation mechanism of calcium-silicate hydrates determined by deviatoric-stress Raman spectroscopy

Creep of the cement matrix affects structural stability concrete. In Portland cements, creep is largely controlled by binding phase calcium-(aluminum-)silicate-hydrate, or C-(A-)S-H. This has a lamellar structure and under deviatoric stress aligns its c -axis with principal stress. However, limiting resistance to this reorientation unknown at nanocrystalline level. Small-angle X-ray scattering shows that lamellae thickness decreases 100's MPa Deviatoric Raman spectroscopy there are two ways break-up can occur. If material's silicate chains cross-linked, then strain in Si O bonds does not increase above certain stresses, indicating relaxation adjacent bond. broken up rastering against each other, introducing defects. These results show plastic deformation C-(A-)S-H relevant for creep. Deviatoric-stress how hydrates way they plastically deform. • samples were characterized bond grain Small angle showed 720 reduced 30%. In-situ cross-linked C-A-S-H slips along intralayer. in-situ C-S-H interlayer. also growth CaCO 3 , fracture both samples.