The rapid-hardening method employing the injection of calcium sulfoaluminate (CSA) cement mortar into voids between preplaced ballast aggregates has recently emerged as a promising approach for the renovation of existing ballasted railway tracks to concrete tracks. This method typically involves the use of a redispersible polymer powder to enhance the durability of the resulting recycled aggregate concrete. However, the effects of the amount of polymer on the mechanical and durability properties of recycled ballast aggregate concrete were not clearly understood. In addition, the effects of the cleanness condition of ballast aggregates were never examined. This study aimed at investigating these two aspects through compression and flexure tests, shrinkage tests, freezing–thawing resistance tests, and optical microscopy. The results revealed that an increase in the amount of polymer generally decreased the compressive strength at the curing age of 28 days. However, the use of a higher polymer ratio enhanced the modulus of rupture, freezing–thawing resistance, and shrinkage resistance, likely because it improved the microstructure of the interfacial transition zones between recycled ballast aggregates and injected mortar. In addition, a higher cleanness level of ballast aggregates generally improved the mechanical and durability qualities of concrete.

中文翻译：

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可再分散聚合物粉体对再生铁路道碴预置骨料混凝土力学和耐久性能的影响

将硫铝酸钙 (CSA) 水泥砂浆注入预先放置的道碴骨料之间的空隙中的快速硬化方法最近已成为将现有有碴铁路轨道改造为混凝土轨道的有前途的方法。这种方法通常涉及使用可再分散的聚合物粉末来提高所得再生骨料混凝土的耐久性。然而，聚合物用量对再生道碴骨料混凝土机械和耐久性性能的影响尚不清楚。此外，从未检查过道碴骨料清洁条件的影响。本研究旨在通过压缩和弯曲试验、收缩试验、抗冻融试验和光学显微镜研究这两个方面。结果表明，聚合物用量的增加通常会降低 28 天固化龄时的抗压强度。然而，使用较高的聚合物比例提高了断裂模量、抗冻融性和抗收缩性，这可能是因为它改善了再生道碴骨料和注入砂浆之间的界面过渡区的微观结构。此外，较高清洁度的压载骨料通常会改善混凝土的机械和耐久性质量。可能是因为它改善了再生道碴骨料和注入砂浆之间界面过渡区的微观结构。此外，较高清洁度的压载骨料通常会改善混凝土的机械和耐久性质量。可能是因为它改善了再生道碴骨料和注入砂浆之间界面过渡区的微观结构。此外，较高清洁度的压载骨料通常会改善混凝土的机械和耐久性质量。