New insights of ordered packing bricks-like structure in 3-aminopropyltriethoxysilane modified calcium silicate hydrate systems

The natural shell structure shows organic matter regulating nano-grain ordered orientation boosts inorganic material toughness. The potential strategy to enhance the toughness of cement involves tailoring the ordered packing of calcium silicate hydrate (C–S–H). However, the mechanism to achieve ordered packing of C–S–H is still limited. Here, we report a method to modify the self-assembly pathway by utilizing high content of 3-aminopropyltriethoxysilane (APTES) at the nanoscale, ultimately attaining the ordered packing of C-S-H nanostructures. The evolution of the crystal phase, chemical structure, morphology and nanomechanical properties was systematically analysed. The results demonstrate the particles of APTES-modified C–S–H exhibit a ‘brick-mixed’ structure similar to nanostructured shells. These brick-like C–S–H nanoparticles are aligned in the same direction, separated by a low elastic modulus binding layer between adjacent bricks. The modified brick-like C-S-H exhibited a remarkably high elastic modulus above 60.0 GPa, significantly surpassing that of classic C-S-H. The modification of the self-assembly pathway are influenced by APTES content and curing time. And hydrogen bonding plays a crucial role in shaping the packing system of C–S–H. This study provides fundamental data and insights into mechanisms for developing new cementitious materials with enhanced toughness.