Study on the effect of hydrated lime content and fineness on asphalt properties

Hydrated lime is known to be an effective moisture damage additive, and it can also reduce the chemical ageing of the bitumen and stiffen the mastic. However, the optimum content and fineness of hydrated lime used in asphalt have been rarely studied. In order to determine the effect of lime content and fineness on hydrated lime modified asphalt and select the optimum lime content and fineness, XD90 asphalt, granite and 200 mesh, 300 mesh and 400 mesh lime with different lime content were chosen as experimental materials. At first, according to surface free energy method, the adhesion work W a was chosen as the main index to evaluate the adhesion between asphalt and granite, and the asphalt surface free energy components after hydrated lime modification were tested. After that, basic technical properties of hydrated lime modified asphalt were studied to refine lime content and fineness. Finally, multiple stress creep and recovery and linear amplitude sweep tests were carried out respectively to study rheological properties of hydrated lime modified asphalt. The results showed that the asphalt adhesiveness increased with the increase of lime fineness, and the optimum lime content for asphalt adhesiveness was around 10%. Moreover, hydrated lime could raise the asphalt viscosity and stiffen asphalt. To make ductility meet the specification requirements, the lime content should be controlled below 10%. When lime content was around 3%–10%, hydrated lime modified asphalt had relatively good rheological properties compared with base asphalt. Meanwhile, the high temperature performance together with the ability to resist permanent deformation was improved apparently. In conclusion, taking into account the adhesion, rheology and basic properties of hydrated lime modified asphalt, the optimum lime content and fineness could be finally determined.