改性再生骨料对自密实混凝土性能的影响

摘要

为提高再生骨料的性能，使之适用于自密实混凝土，使用4种强化手段对简单破碎后的两种来源再生骨料进行改性处理，研究其对新配RA⁃SCC工作性能和硬化后物理力学等性能的影响。结果发现：骨料来源和原生混凝土强度对再生骨料的品质有较大影响，而经过改性处理以后，不同来源的再生骨料品质都有所提升，所制成的RA⁃SCC性能差异变小；裹浆法以及水玻璃浸泡的方法能够较大程度地改善新拌RA⁃SCC的自密实性能；高温煅烧法、酸性溶液浸泡法、水玻璃分散技术可使硬化后的RA⁃SCC内部结构更加致密，从而明显改善了RA⁃SCC的抗拉强度、抗干燥收缩性能和抗冻性能，但大部分骨料增强技术对RA⁃SCC的抗压强度和弹性模量的影响较小。%To improve the recycled concrete aggregates ( RA) quality for using in self⁃compacting concrete ( SCC) , the effect of four alternative treatment methods of RA with two sources on the fresh and hardened properties of RA⁃SCC were evaluated. The result shows that the RA sources and parent concrete strength has great influence on the quality and properties of RA. While after the pretreatment of RA, the RA qualities from different sources are improved and the performance difference of RA⁃SCC becomes small. The presoaking in the water glass dispersion and cement⁃fly ash slurry can significantly improve self⁃consolidating characteristics of fresh RA⁃SCC. The thermal expansion method, low⁃concentration acid dissolution method and water glass dispersion method provide denser and connected microstructures leading to the significant improvement in tensile strength, dry shrinkage resistance and frost resistance of RA⁃SCC. Most enhancement methods have a limited effect on compressive strength and modulus of elasticity.