Calcium Silicate Hydrate gel (C-S-H) is the basic product of the cement hydration process responsible for strength and durability of concrete. Synthetic C-S-H was synthesized by mixing Calcium oxide (CaO denoted as C) and silicate (SiO₂ denoted as S) with a C/S mixture ratio of 1.5. C-S-H powder was filtered, and dried to a relative humidity of 11% and then compacted at 400 MPa. Nanoindentation tests incorporating time-dependent effect (creep) were performed on polished C-S-H specimens using Berkovich indenter tip. The reduced elastic modulus and creep compliance of C-S-H specimens were extracted from nanoindentation measurements. An innovative approach is suggested to extract cracking energy. A viscoelastic-plastic finite element model was developed to simulate the nanoindentation of C-S-H incorporating creep and cracking. The finite element model was used to isolate the viscoelastic from the cracking energy components. The proposed approach enabled estimating fracture toughness of C-S-H.