Mechanical properties and microscopic mechanisms of deposited nanocarbon reinforced cement mortar

Carbon nanomaterials opens a novel pathway for enhancing the mechanical properties and reinforcement effectiveness of cement-based materials. However, due to their high cost and reliance on specialized production processes, carbon nanomaterials have not been widely applied in practical engineering. Therefore, deposited nanocarbon (DNC), a byproduct of hydrogen production via methane pyrolysis, is utilized to enhance the performance of cement mortar. In this study, through uniaxial compression tests combined with acoustic emission (AE) technology, the entire fracture process of cement mortar with varying DNC dosages was comprehensively monitored. Microscopic characterization of the fracture surface was conducted using scanning electron microscopy. Scanning electron microscopy was employed to conduct microscopic characterization of the fracture surface, cement hydration products, and the bonding condition of slurry-aggregate interface. The results indicate that the compressive strength of DNC-modified cement mortar increases by 6.3–31.5 %, and the elastic modulus increases by 17.9–34.6 %. Additionally, the incorporation of DNC effectively reduces the AE counts during the early stages of sample failure. Furthermore, DNC promotes the formation of denser hydration products, filling voids and reducing micro-cracks and micro-pores in the hardened cement paste. This effectively reduces the width of the interfacial transition zone (ITZ) between fly ash and cement paste (by approximately 30.4–52.0 %), enhancing the interfacial bonding performance between the aggregate and the hardened cement paste. The proposed use of DNC offers a novel approach for achieving efficient resource recycling, promoting the widespread application of nanocarbon-modified cement mortar, and fostering sustainable development.