Cement-supplementary cementitious materials (SCM)/graphene oxide (GO) combine a lower carbon footprint with ductility enhancement. Aluminum phase released during the SCM hydration occurs in various forms in C-A-S-H/GO. The effects of bridging Al(Q2b) and interlayer Alinter on the mechanical properties of C-A-S-H/GO were investigated based on the reactive molecular dynamics. It is indicated that Alinter with less than Al(Q2b) redistributes the stress during the fracture of the system, activating load sharing between the layers, and thus triggering a “recovery-reinforcement” mechanism to multiply the mechanical properties. The “recovery-reinforcement” can be explained via analyzing Al's contribution to the reorganization of the interfacial bonding network and the chemical bonding evolution during fracture. The results show that the targeted regulation of Al chemical environment in cement-SCM/GO preparation is a key issue to break the ductility bottleneck.