石灰岩矿粉性质对沥青胶浆性能的影响因素及其技术标准

Influence of limestone mineral powder properties on asphalt mortar performance and its technical standards

摘要:

为了确定石灰岩矿粉性质中影响沥青胶浆抗冻性能的主要因素,并制定石灰岩矿粉分级和选用原则,对不同类型矿粉的沥青胶浆进行了冻融循环试验,分别检测其冻融前后的化学成分、微观形貌、微观力学性质和流变性能的变化,并对试验结果进行随机森林分析。结果表明:矿粉的掺入能够改善沥青胶浆的冻融老化性能,冻融循环后,胶浆粗糙度下降幅度、表面模量提升幅度与矿粉CaCO₃含量（质量分数）呈抛物线下降趋势,沥青胶浆黏附力与矿粉CaCO₃含量呈直线下降关系,为保持沥青胶浆冻融后性能的稳定,矿粉的CaCO₃含量不应低于85%；季冻区的沥青路面比非季冻区更容易发生水损害,与非季冻区相比,季冻区矿粉中CaCO₃含量应提高10%。随机森林方法分析表明,矿粉的物理化学性质对胶浆性能影响的程度排序为比表面积>CaCO₃含量>细度指标>塑性指数,比表面积影响沥青与矿粉的反应速度,而CaCO₃含量影响其反应的充分性。所提出的石灰岩矿粉母岩技术要求与矿粉的综合分级技术标准,可指导路用矿粉的分级、选用和生产控制。

Abstract:

To investigate the main factors affecting the anti-frost properties of asphalt mortar and provide classification and selection principle for limestone powder, we carried out freezing-thawing cycle tests on asphalt mortar with different types of mineral powder. The chemical composition, microscopic morphology, microscopic mechanical property, and rheological property were detected during the freezing-thawing cycles, and random forest analysis was conducted on the test results. Results showed that the addition of mineral powder improved the anti-aging properties of asphalt mortar during freezing and thawing. After freezing-thawing cycles, the decrease in mortar roughness and the increase in surface modulus showed a downward-parabolic trend with the content of CaCO₃ (mass fraction), while the adhesion decreased linearly with the content of CaCO₃. The CaCO₃ content of mineral powder should not be less than 85%, so as to maintain the stability of asphalt mortar properties after freezing-thawing cycles. Asphalt pavement moisture damage was more likely to occur in seasonal frozen area than in non-seasonal frozen area. Compared with non-seasonal frozen area, the CaCO₃ content of mineral powder in seasonal frozen area should be increased by 10%. Random forest analysis showed that the ranking of influence factors of physical and chemical indexes of mineral powder on the properties of mortar were specific surface area (SSA) > CaCO₃ content (CC) > fineness index (X₉₀) > index of plasticity (IP). Specific surface area affected the reaction rate of asphalt and mineral powder, while CaCO₃ content affected the adequacy of the reaction. The technical requirements of limestone rocks and the comprehensive classification technical standards of mineral powder were proposed, which can guide the classification, selection, and production of mineral powder for road usage.