Abstract
High‐viscosity modified asphalt (HVA) is widely used as the binder for permeable asphalt pavement, and hydrated lime (HL) attracts a strong technical interest as an effective moisture additive in asphalt for a long time. However, the application of HL in HVA has been rarely studied. The present study evaluates the influence of HL on the high‐temperature rheological properties of HVA and selects the optimum HL content and fineness. The asphalt mortars of HVA and HL of different contents and fineness were prepared. Temperature scanning (DSR‐TS), multiple stress creep recovery (MSCR) by using a dynamic shear rheometer, and scanning electron microscope (SEM) tests were carried out to evaluate the high‐temperature rheological properties and microstructure morphology characteristics of the asphalt mortars. Based on the DSR‐TS and MSCR tests, the results showed that high‐temperature performance together with the ability to deformation resistance of HVA was improved apparently with the increase of the HL content. When the HL content is above 1.2, the stress sensitivity of HVA is lower. The SEM results clearly showed that the uniformity of asphalt mortars could be effectively guaranteed when the HL content was 1.2 and the fineness was 800 mesh. The HL fineness has little effect on the high‐temperature performance of HVA. In summary, taking into account the high‐temperature performance and microstructure of HVA with HL, the optimum HL content and fineness could be finally determined.
Highlights
An asphalt mixture comprises a three-phase inhomogeneous material matrix, including asphalt binder, graded mineral aggregates, and air voids [1, 2]
Δ of asphalt mortar #3 (AM3) is the largest, and δ of others increases with the increase of the hydrated lime (HL) content. is is because the asphalt mortar has not been transformed into a fluid at 30°C–60°C, and the resistance of asphalt mortar to deformation increases with the addition of HL
At 60°C–120°C, δ of asphalt mortar with different contents of HL increases linearly with the increase of temperature. δ of samples asphalt mortar #1 (AM1), asphalt mortar #2 (AM2), AM3, and asphalt mortar #4 (AM4) is less susceptible to the changes of the HL content. is result shows that the high-viscosity modified asphalt (HVA) in the mortar is mainly viscous, and the influence of the HL content on the viscosity is very small at 60°C–120°C
Summary
An asphalt mixture comprises a three-phase inhomogeneous material matrix, including asphalt binder, graded mineral aggregates, and air voids [1, 2]. In China, due to the heavy traffic axle load and the complete climate environment, high-viscosity modified asphalt (HVA) is commonly used as the asphalt binder to increase the performance of the porous asphalt mixture for the drainage asphalt pavement, which solves the problems of scattering and spalling when using ordinary modified asphalt to build the drainage asphalt pavement [5]. HL is a well-known material for improving the resistance against moisture and frost damage of asphalt mixtures in which its application dates back to the 1970s [10,11,12]. When the aggregate surface is humid or the water content in the air is high, HL reacts with water and carbon dioxide in the air to form calcium carbonate, which makes the aggregate and asphalt have a stronger adhesion and resist the water damage of the asphalt mixture [13]
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