▎ 摘　　要

Graphene oxide (GO) efficiently enhances macroscale mechanical properties of cement-based materials. Yet the nanoscale reinforcing mechanism of GO for calcium silicate hydrate (C-S-H), the key binding phase of concrete, remains poorly understood. Moreover, how polycarboxylate ether (PCE)-based superplasticizers affect the nanomechanical properties of C-S-H remains unclear. The intrinsic mechanical properties of the nanocomposites are measured using high-pressure X-ray diffraction. The influences of GO and PCE on the local Ca and Si en-vironments are probed using X-ray absorption spectroscopy. For the first time, we evidence that PCE-induced well-dispersed GO nanoplatelets strengthen the C-S-H basal planes, whereas poorly water-dispersed GO weakly interacts with basal planes and does not strengthen in plane Ca-O bonds. Both PCE and GO only slightly strengthen C-S-H's c-axis. The bulk modulus of C-S-H/PCE/GO nanocomposite is 190% than pure C-S-H. Func-tional groups of PCE and GO prefer interacting with the Ca-O sheets of C-S-Hs instead of silicate tetrahedra.