Comparative evaluation on decay process of asphalt-aggregate interfaces under solution erosion

• Published in: Construction & building materials Vol. 400; p. 132698
• Main Authors: Li, Chen, Qin, Wen, Fu, Zhen, Dai, Jiasheng, Ma, Feng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 12.10.2023
• Subjects: Adhesion and cohesion; Asphalt; Moisture damage; Molecular dynamic simulation; Asphalt; Moisture damage; Molecular dynamic simulation; Adhesion and cohesion
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.132698

•The adhesion failure occurs earlier than that of cohesive failure caused by solution, which has been verified at the atomic scale.•The moisture sensitivity of mastic with different filler/binder ratio of interface has the respective characteristic.•Alkali solution deteriorates the most towards bitumen, bitumen-base and bitumen-aggregate interfaces. In order to analyze the decay process of fractions of asphalt mixture caused by solution erosion, molecular dynamics (MD) simulations and dynamic shear rheometer (DSR) tests were conducted to study the solution-induced response. The settled environments are salt, pure water, and alkali solutions, respectively. The cohesive failure of asphalt-solution-asphalt (A system), adhesive failure of asphalt-solution-quartz/calcite aggregate (B-1 and B-2 systems), and “water-aging” of bitumen and mastic were thereby concluded. Results show that the asphalt-base system has less susceptibility towards solution as compared to aggregate-base system, where the calcite-base one possesses the lowest energy ratio (ER) value, namely the least moisture resistance. Thus, adhesion failure of alkaline aggregate usually occurs first, while cohesive bonding in asphalt is considerably stable. Besides, the diffusion coefficient (D) value of SARA in asphalt-aggregate keeps higher than that in asphalt-base system, where water molecules have a stronger intervention effect. By constructing the master curves of complex shear modules (G*) via laboratory DSR results, it is verified that with the increase of erosion days, solution has “water aging” effect on virgin and SBS asphalt/mastic, and alkali solution performs the most deterioration. Here, mastic with 1.2 filler/bitumen ratio (FBR) maintains the most stable solution erosion resistance.