氧化石墨烯对水泥砂浆抗碳化性能的影响

The Influence of Graphene Oxide on the Carbonation Resistance of Cement Mortar

摘要: 为评估氧化石墨烯(GO)对水泥砂浆力学性能与长龄期抗碳化能力的影响，本文在固定水灰比与砂胶比条件下设置不同GO掺量砂浆，开展标准养护抗压强度试验与加速碳化试验，并结合XRD、FTIR和SEM对碳化产物及微观形貌进行表征。结果表明，适量GO可提高砂浆早期与28 d抗压强度，并呈现“适量最优、过量回落”的掺量效应，其中0.05%掺量组(P05)在28 d抗压强度由对照组的50.74 MPa提升至54.58 MPa (提高约7.6%)，表现最优。同时GO能有效降低碳化深度与碳化系数，显著抑制碳化前沿推进。碳化龄期强度整体随暴露时间增加而上升，但GO组的强度增益幅度相对减小，说明GO降低了碳化导致的二次致密化程度。微观分析显示，掺GO后碳酸盐特征相对减弱，碳化产物更倾向于在裂缝等局部区域富集而非在基体内广泛沉积，表明GO主要通过孔结构致密化与传输路径增曲折度提升砂浆抗碳化性能。综合力学与耐久性表现，本研究条件下0.05%左右为更优掺量区间。

Abstract: To evaluate the influence of graphene oxide (GO) on the mechanical properties and long-term carbonation resistance of cement mortar, mortar mixtures incorporating different GO dosages were prepared under a fixed water-to-cement ratio and sand-to-binder ratio. Compressive strength tests under standard curing and accelerated carbonation tests were conducted, and the carbonation products and microstructural features were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that an appropriate amount of GO enhances early-age and 28-day compressive strength, exhibiting a dosage-dependent trend of “optimum at moderate dosage and reduction at excessive dosage.” Specifically, the 0.05% GO mixture (P05) achieved the best performance, increasing the 28-day compressive strength from 50.74 MPa (control) to 54.58 MPa (approximately 7.6%). In addition, GO effectively reduces carbonation depth and the carbonation coefficient, significantly suppressing the advance of the carbonation front. Although compressive strength generally increases with carbonation exposure time, the strength gain in GO-modified mortars is relatively smaller, suggesting that GO mitigates the secondary densification induced by carbonation. Microstructural observations further show weakened carbonate-related signatures after GO incorporation, and carbonation products tend to accumulate locally (e.g., near cracks) rather than depositing extensively throughout the matrix. This indicates that GO primarily improves carbonation resistance by densifying the pore structure and increasing the tortuosity of transport pathways. Considering both mechanical performance and durability, an optimal GO dosage of approximately 0.05% is recommended under the conditions investigated.