APTES/Calcium silica hydrate nano-hybrid composites with enhanced mechanical properties

Reducing the cement content in the concrete mix by developing cementitious materials with enhanced properties can contribute considerably to cut the CO2 emissions produced by the cement industry. In this work, we used a bottom-up approach to enhance the mechanical performance of the calcium silicate hydrate (C-S-H), by the covalent bonding of the 3-aminopropyltriethoxysilane (APTES), to create a nano-hybrid C-S-H/APTES. The intercalation of APTES within the C-S-H contributes to increase the bulk modulus by 35 % due to the stiffening along all the lattice directions. The stiffer behavior along a- and b- lattice directions is due to the formation of covalent bonds between the APTES molecules and the non-bonding oxygens of the C-S-H, blocking the silicate chain relaxation and increasing the overall stiffness of the ab-plane. In the c-direction, the stiffening is attributed to the densification of the hydrogen bond network in the interlaminar space caused by the APTES intercalation.