基于碳酸化钢渣集料的沥青混凝土体积稳定性研究

针对沥青道路用钢渣集料的安定性不良问题，研究了碳酸化钢渣的沥青混合料体积膨胀率的变化规律，探讨了碳酸化钢渣中f-CaO含量和压蒸粉化率的变化规律和相互关系，利用背散射电子成像（BSE）、扫描电子显微镜（SEM）结合X射线能谱（EDS）分析了碳酸化钢渣的微观形貌。结果表明：在CO₂初始压力1.0 MPa下，温度低于90 ℃碳酸化主要消解钢渣中活性f-CaO，生成的立方体状CaCO₃颗粒尺寸较大且均匀，碳酸化钢渣中f-CaO含量与其压蒸粉化率呈直线下降相关。温度高于90 ℃和时间长于9 h碳酸化制度可完全消解4.75~9.5 mm钢渣中的活性f-CaO，同时逐渐消解f-MgO或RO相，致使碳酸化钢渣的压蒸粉化率直线下降；并且促使大颗粒聚集矿物向小尺寸分裂和重排，促进短簇状的夹杂MgCO₃、FeCO₃等物质的CaCO₃生成。最终，碳酸化温度高于90℃和时间长于9 h可从根本上解决钢渣安定性不良的问题，其沥青混合料养护3 d体积膨胀率（约0.97%）低于标准值（1.5%）的35%，6 d膨胀率（约1.16%）趋于平稳并低于标准值的23%，达到了碳酸化钢渣沥青混凝土具有长期良好稳定性的目的。

Study on Volume Stability of Asphalt Concrete Based on Carbonated Steel Slag Aggregate

Aiming at the unsoundness problem of steel slag aggregates for asphalt roads,the volume expansion rate of the asphalt mixture for carbonated steel slag was studied.The variation and relationship between f-CaO content and autoclaving pulverization rate in carbonated steel slag were investigated.The micro-morphology of carbonated steel slag was analyzed by BSE(Back Scattered Electron),SEM(Scanning Electron Microscope) and EDS(Energy X-ray Dispersive Spectroscopy).The results show that the active f-CaO in steel slag is mainly digested by carbonation below 90 °C under 1.0 MPa CO₂ initial pressure,and the cubic CaCO₃ particles are big size and uniform.The content of f-CaO in carbonated steel slag decreases linearly with its autoclaved pulverization rate.The active f-CaO in 4.75~9.5 mm steel slag can be completely digested by the carbonation system with temperature higher than 90 °C and time longer than 9 h,and the f-MgO or RO phase can be gradually digested,resulting in a linear decrease in the autoclave pulverization rate of carbonated steel slag.It also promotes the splitting and rearrangement of large aggregate minerals to small size and promotes the formation of CaCO₃ with short clusters of inclusions such as MgCO₃ and FeCO₃.Finally,the unsoundness problem of steel slag can be fundamentally solved when the carbonation temperature is higher than 90 ℃ and the time is longer than 9 h.The volume expansion rate of asphalt mixture cured for 3 d (about 0.97 %) is lower than 35 % of the standard value (1.5 %),and the expansion rate of 6 d (about 1.16 %) tends to be stable and lower than 23 % of the standard value,which achieves the purpose of long-term good stability of steel slag asphalt concrete.