曾辉, 沈泽涵, 郅晓, 黄毅, 李婷玉, 陈宇亮, 肖源杰. 钢渣骨料多孔结构对沥青混合料低温抗裂性能的影响机制[J]. 北京工业大学学报. doi: 10.11936/bjutxb2023060007
    引用本文: 曾辉, 沈泽涵, 郅晓, 黄毅, 李婷玉, 陈宇亮, 肖源杰. 钢渣骨料多孔结构对沥青混合料低温抗裂性能的影响机制[J]. 北京工业大学学报. doi: 10.11936/bjutxb2023060007
    ZENG Hui, SHEN Zehan, ZHI Xiao, HUANG Yi, LI Tingyu, CHEN Yuliang, XIAO Yuanjie. Investigating Mechanisms of Porous Structure of Steel Slag Affecting Low-temperature Crack Resistance of Asphalt Mixture[J]. Journal of Beijing University of Technology. doi: 10.11936/bjutxb2023060007
    Citation: ZENG Hui, SHEN Zehan, ZHI Xiao, HUANG Yi, LI Tingyu, CHEN Yuliang, XIAO Yuanjie. Investigating Mechanisms of Porous Structure of Steel Slag Affecting Low-temperature Crack Resistance of Asphalt Mixture[J]. Journal of Beijing University of Technology. doi: 10.11936/bjutxb2023060007

    钢渣骨料多孔结构对沥青混合料低温抗裂性能的影响机制

    Investigating Mechanisms of Porous Structure of Steel Slag Affecting Low-temperature Crack Resistance of Asphalt Mixture

    • 摘要: 钢渣骨料的多孔结构对沥青混合料低温抗裂性能影响的宏细观机制尚不掌握,不利于钢渣骨料沥青路面长期性能的有效保持。针对此不足,基于室内低温弯曲试验,构建了可表征钢渣骨料多孔结构的沥青混合料小梁试样精细化离散元模型,进而开展了不同的钢渣孔隙率和开口孔隙沥青填充度下的虚拟低温弯曲试验,量化分析了钢渣多孔结构对试样整体强度和细观断裂性能的影响规律及机制。试验研究结果表明多孔钢渣骨料仅可替代粒径> 2.36 mm的粗骨料,控制钢渣加热温度并延长湿拌时间可确保沥青胶浆充分填充钢渣骨料表面孔隙;离散元数值模拟结果表明钢渣骨料表面开口孔隙附近出现应力集中,裂缝贯通钢渣开口孔隙;钢渣骨料表面孔隙率越高,则峰值应力越低,裂缝越易从开口孔隙处发育;峰值应力随钢渣骨料表面开口孔隙沥青胶浆填充度的降低而显著降低;钢渣骨料表面孔隙对沥青胶浆的吸收作用会显著影响裂缝萌生路径及混合料的低温抗裂性能,裂缝易在钢渣孔洞附近萌生,且开口孔隙无沥青填充时此裂缝扩展特征更明显;钢渣骨料表面孔隙可增强沥青-钢渣界面的黏结性能,但开口孔隙过大会导致应力集中且易萌生裂缝。在实际工程中建议控制大孔隙钢渣骨料含量,并确保沥青砂浆充分填充钢渣骨料表面孔隙,以提高其低温抗裂性能。

       

      Abstract: The macroscopic and microscopic mechanisms of porous structure of steel slag aggregates affecting low-temperature crack resistance of asphalt mixtures remain unexplored, hindering the effective maintenance of long-term performance of asphalt pavements incorporating steel slags. To address this deficiency, based on the results of laboratory low-temperature beam bending tests on asphalt mixtures incorporating steel slags (AMISS), a refined discrete element method (DEM) model of AMISS was established characterizing the porous structure of steel slag aggregates. DEM simulations of low- temperature beam bending tests were performed under different levels of surface pores of steel slags and absorbed asphalt by surface pores to quantitatively analyze the influence patterns and mechanisms of steel slag aggregates surface pore structure on the fracture strength and micro-crack evolution characteristics of the specimens. Laboratory test results indicate that porous steel slag aggregates can only replace coarse aggregates larger than 2. 36 mm, and that controlling the heating temperature of steel slags and extending the wet mixing time can ensure adequate absorption of asphalt binder by surface pores of steel slag aggregates. Numerical simulation results show that stress concentration occurs near the open surface pores of steel slag aggregates with micro-cracks propagating through the open surface pores. As the surface porosity of steel slag aggregates increases, the peak stress decreases, and micro-cracks are more likely to initiate around the open pores. The peak stress significantly decreases with decreasing level of absorbed asphalt by the open pores. The absorption of asphalt binder by the surface pores of steel slag aggregates significantly influences the low-temperature crack resistance of AMISS, especially micro-cracks tend to initiate from the open pores. This crack extension feature is more obvious when the open pores are barely filled by asphalt binder. The surface pores enhance the slag-asphalt interface bonding. However, larger open pores lead to stress concentration, making it easier for cracks to initiate in their vicinities. Therefore, it is recommended to control the content of steel slag aggregates with large open surface pores. In pavement applications, the amount of asphalt binder added into the drum drying the steel slags and the wet mixing time should be well controlled based on the natural moisture content of the steel slag aggregates to ensure low-temperature crack resistance of AMISS.

       

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