Influence of graphene oxide on the self-healing of cement paste fractures in CCUS cementing: A combined analysis of experiments and molecular dynamics simulations

•GO improves the self-healing rate of cement compressive strength in a CCUS environment.•GO improves cement’s ability to adsorb CO2 and accelerates CO2 diffusion.•GO serves as the nucleation point for CaCO3 crystals, allowing cement cracks to self-healing. Cracking the cement paste for CCUS cementing can jeopardize the integrity of the wellbore, jeopardizing CO2 storage security. After carbonization and self-healing for 28 days, the experimental results indicate that cement's compressive strength growth rate combined with 0.10 wt% GO reached 1077%, whereas, in the control group, it reached only 850%. More CaCO3 crystals developed on the crack surface of GO cement as the carbonization self-healing time increased than in the control group. The self-healing volume of GO cement cracks was 74.3%, higher than the control group (34.5%). The molecular simulation results indicate that GO can enhance the capacity of cement-based materials to absorb CO2 and speed up CO2 diffusion. GO supplies nucleation sites for CaCO3 crystals and accelerates the carbonization self-healing process of cracks.