纳米CSH⁃PCE溶液处理再生骨料对再生骨料自密实混凝土力学性能与耐久性的影响

Effect of Recycled Aggregate Treated with Nano CSH⁃PCE Solution on Mechanical Properties and Durability of Recycled Coarse Aggregate Self⁃compacting Concrete

为了提高再生骨料在自密实混凝土中的利用率,对纳米CSH-PCE溶液处理的再生骨料对再生骨料自密实混凝土(RCASCC)的工作性能、抗压强度、抗气体渗透性、抗氯离子渗透性、毛细吸水、抗冻融性的影响进行试验研究,并结合扫描电镜探讨了纳米CSH-PCE溶液作用的微观机理。结果表明:纳米CSH-PCE溶液处理的再生骨料对RCASCC的工作性能影响较小,能有效提升其抗压强度和耐久性能。随着处理再生骨料的纳米CSH-PCE溶液浓度从1%升高至20%,再生自密实混凝土的抗压强度先增大后减小。当纳米CSH-PCE溶液浓度为7%时,再生混凝土的28d抗压强度达到最大值。其原因是再生骨料表面的纳米CSH-PCE晶核颗粒为再生骨料与新浆体之间的界面提供成核位点,促进水泥水化,且晶核颗粒粒径很小,可填充界面过渡区的孔隙,使基体结构更密实。

To improve the utilization of recycled aggregates in self-compacting concrete,the effects of Nano-CSH-PCE solution-treated recycled aggregates on the workability,compressive strength,gas permeability,chloride ion permeability,capillary absorption,and freeze-thaw resistance of recycled coarse aggregate self-compacting concrete(RCASCC)were investigated experimentally and combined with scanning electron microscopy to explore the microscopic mechanism of the action of Nano-CSH-PCE solution.The results show that the Nano-CSH-PCE solution treating recycled aggregates has a small effect on the working performance of RCASCC,and can effectively improve its compressive strength and durability performance.As the concentration of Nano-CSH-PCE solution treating recycled aggregates increased from 1%to 20%,the compressive strength of recycled self-compacting concrete first increased and then decreased.When the concentration of Nano-CSH-PCE solution was 7%,the 28d compressive strength of the recycled concrete reached the maximum value.The reason for this is that the Nano-CSH-PCE nucleation particles on the surface of the recycled aggregate provide nucleation sites for the interface between the recycled aggregate and the new slurry to promote cement hydration,and the small particle size of the nucleation particles can fill the pores in the interface transition zone and make the matrix structure denser.