1- Professor, Highway Engineering Group , kavussia@modares.ac.ir
2- PhD Student
3- Associate Professor
2- PhD Student
3- Associate Professor
Abstract: (405 Views)
Nanomaterials have been used in the recent years to improve rheological properties of the asphalt binders and increase mechanical properties of the asphalt mixtures. The high cost of producing nanomaterials is one of the major obstacles that has limited their application in road pavements. In this research, two methods of producing nanomaterials have been applied to produce nano hydrated lime (NHL). The first method was a mechanical process of milling hydrated lime with the application of a planetary ball mill. The second method was chemical processing of dissolving certain chemical materials (namely, calcium nitrate Ca(NO3)2, sodium hydroxide NaOH and sodium dodecyl sulfate SDS) into distilled water. The process resulted in the production of NHL solution that after drying in an oven resulted in NHL particles. The sizes of the NHL products were measured using two methods of Field Emission Scanning Electron Microscope (FE-SEM) and Dynamic Light Scattering (DLS). The size analysis was performed on NHL samples that were produced after different milling periods in the physical method; and, variation of the concentration of the solution, mainly calcium nitrate and SDS, in the chemical method. The average particle sizes in the physical method, after 6 hours of milling, were 211 nm, as measures in DLS and 114 nm as measured in FE-SEM. These in the chemical method, at concentration of 3 ml of calcium nitrate solution (Ca(NO3)2), were 379 and 124.615 nm respectively. With the chemical method, the nano particles were formed in the plate form with average thickness of 68.5 nm. In addition, X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis were performed in order to determine the composition of the produced nano materials. These indicated that with the physical method, a higher lime content material was produced. With the aim of assessing the effectiveness of the produced NHL materials to modify asphalt binders, a 60-70 and an 85-100 penetration grade were used and nano modified binders containing 2, 4 and 6% NHL were prepared and were tested under standard bitumen tests and viscosity determination. The results indicated that with adding NHL to the asphalt binders, penetration was reduced and softening point was increased. In addition, the temperature susceptibility of the modified binders were reduced too. Assessing the change of the viscosity of the NHL modified binders, it resulted that 4% NHL would provide the optimum conditions.
Keywords: Nano-hydrated lime (NHL), Milling process (physical), Dissolution process (chemical), Nanoparticles size, Asphalt binder physical properties
Article Type: Original Research |
Subject:
Roads and Transportation
Received: 2024/04/13 | Accepted: 2024/07/22
Received: 2024/04/13 | Accepted: 2024/07/22
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