石墨烯改性沥青路用性能提升及其机理

Pavement property improvement of graphene modified asphalt andits improving mechanism

为了探究石墨烯对沥青路用性能的提升及其机理,利用分散剂二甲基亚砜(DMSO)预处理石墨烯,提高其在沥青中的分散性,再采用DMSO预处理石墨烯(DG)添加到70#道路石油沥青(70#沥青)中制备DG改性沥青。通过常规物理性能试验、黏韧性试验、直接拉伸试验和原子力显微镜对70#沥青和DG改性沥青进行测试,评价DG对沥青路用性能增强效果,并从微观角度分析DG对沥青微观结构的影响,揭示DG对沥青路用性能提升机理。结果表明,加入的DG降低了沥青的针入度和延度,但是提高了沥青的软化点。由于DG具有较大的表面能,吸附了沥青中的轻组分而形成插层结构,致使DG改性沥青上部软化点值和下部软化点值存在差异。DG改性沥青具有较强的黏韧性和韧性,其黏韧性、黏弹性、韧性和韧性比均高于70#沥青,因为被插层后的DG抑制了沥青轻组分的流动,致使DG改性沥青具有较好的抗变形能力。DG的加入使得沥青变硬,降低DG改性沥青表面的粗糙度。由于DG的吸附作用和DG插层结构的限制作用增加了DG改性沥青微观表面蜂状结构数量,导致DG改性沥青表面具有数量更多且体积较小的蜂状结构。受到拉伸作用时,70#沥青中大体积的蜂状结构易产生应力集中,使其力学性能及抗变形能力降低,而DG改性沥青中小体积且数量较多的蜂状结构能够分散受力,提高了DG改性沥青的均匀受力,降低了其应力集中出现的可能,提升了DG改性沥青的路用性能和耐久性。

Carbon nanomaterials are gradually used in pavement engineering.To investigate the improvement mechanism of graphene on pavement properties of asphalt,graphene was pretreated using the dispersant of dimethyl sulfoxide(DMSO)to increase its dispersity in asphalt.Then the DMSO pretreated graphene(DG)was added in 70#pavement petroleum asphalt(70#asphalt)to prepare DG modified asphalt.To evaluate the improvement effects of DG on pavement properties and to analyze the influences of DG on the microstructures of 70#asphalt,conventional physical performance tests,toughness test,direct tensile test and atomic force microscopy(AFM)test were conducted on 70#asphalt and DG modified asphalt,revealing the improvement mechanism of DG on pavement properties of asphalt.Results indicate that the penetration and ductility of asphalt are reduced after the addition of DG,while the softening point is increased.Because of the larger surface energy of DG,DG adsorbs light components in asphalt,and the intercalation structure is formed,resulting in a difference between upper and bottom softening points of DG modified asphalt.DG modified asphalt has stronger toughness and tenacity,as well as its visco-toughness,viscoelasticity,toughness and toughness ratio are all larger than those of 70#asphalt.Also,the flow of light components is inhibited by the intercalation structure of DG,allowing DG modified asphalt to show better deformation resistance.The addition of DG hardens 70#asphalt and reduces the surface roughness of DG modified asphalt.The quantity of bee-like structures on the microscopic surface of DG modified asphalt is increased by the adsorption effects of DG and the restriction effects of the intercalation structure of DG,resulting in large quantity and smaller volumes of bee-like structures on the surface of DG modified asphalt.When DG modified asphalt is subjected to tensile action,the large-volume bee-like structures in 70#asphalt are easily generated to cause the stress concentration,which lowers the mechanical properties of asphalt.The small volume and large quantity of bee-like structures in DG modified asphalt distract the stress,improving the stress uniformity in DG modified asphalt.This reduces the possibility of stress concentration in DG modified asphalt,as well as improves the pavement properties and durability of DG modified asphalt.This study provides an insight into the pavement property improvement of graphene modified asphalt and its improving mechanism.