氧化石墨烯对水泥基材料力学性能的影响及分子动力学模拟

Effect of graphene oxide on the mechanical properties of cement-based materials and its molecular dynamics simulation

通过力学性能试验及扫描电镜(SEM)、 X射线衍射(XRD)等测试手段研究氧化石墨烯(GO)对水泥基材料力学性能及微观结构的影响。结果表明:相对于空白试样,掺量为0.02%的GO能够明显提高水泥净浆试块早期的抗压、抗折强度;同时,GO的掺入改变了氢氧化钙(CH)晶体的聚集状态,细化了CH晶体尺寸,使水泥石结构更加致密。为了从原子/分子层面探究GO对水泥水化反应的影响机理,采用分子动力学模拟软件Materials Studio(MS)模拟水泥水化产物CH在GO表面的移动和聚集状态,以及掺入GO前后CH力学性能的变化。模拟结果显示:随着水化反应的进行,钙离子与氢氧根离子向着亲水含氧基团位点处移动,逐渐聚集在GO分子周围,加速CH晶体的形成;掺入GO后,CH微观结构模型的杨氏模量相比未掺入GO的模型提高了26.9%,说明GO能够有效提升CH水化产物的力学性能。模拟结果与力学和微观性能试验结果具有较高的吻合度。

The effect of graphene oxide(GO) on the mechanical properties and microstructure of cement-basedmaterials is studied through mechanical property test and microscopic test methods such as scanning electron microscope(SEM), X-ray diffraction(XRD). Testing results show that compared with the blank sample, the additionof 0. 02% GO improves the early compressive and flexural strengths of cement paste specimens obviously.Meanwhile, the addition of GO transforms the aggregation state of Ca(OH)2 crystal, refines the size of CH crystaland makes the structure of cement paste more compact. In order to explore the influence mechanism of GO on cementhydration reaction from the atomic/ molecular level, molecular dynamics simulation software Materials Studio(MS) is used to simulate the movement and aggregation of cement hydration products(CH) on the surface of GO.The simulation results show that with the progress of hydration reaction, calcium ions and hydroxyl ions move towardsthe sites of hydrophilic oxygen-containing group, gradually gather around GO molecules and facilitates theformation of CH crystals. With the addition of GO, the Youngs modulus of CH microstructure model increased by26. 9% compared to the model without GO, indicating that GO can effectively improve the mechanical propertiesof CH hydration products. The simulation results are in good agreement with the mechanical and micro performancetest results, which can provide a theoretical reference for the design and application of molecular dynamicssimulation technology in GO cement-based materials.