氯离子与硫酸根离子在水泥浆体中的耦合扩散

Coupled Diffusion Behavior of Chloride and Sulfate Ions in Cement Paste

摘要:

本文研究了不同复合盐环境下Cl?与SO?2?在水泥浆体中的耦合扩散。对于普通硅酸盐水泥浆体，复合氯盐溶液中的SO?2?早期抑制Cl?扩散，但后期转为促进作用；亚硫酸盐中SO?2?抑制Cl?扩散的作用更强，但抑制作用随时间延长减弱。普通硅酸盐水泥浆体对氯离子的吸附能力较弱，SO?2?作用下释放出的自由Cl?更容易向浆体内部扩散，对Cl?总扩散进程影响显著。矿渣-水泥浆体在单、复合氯盐及亚硫酸盐溶液中的180天自由Cl?扩散系数分别为0.96、0.81、0.77×10?12 m2/s。矿渣-水泥浆体对Cl?的吸附能力强，SO?2?作用下表层浆体释放的自由Cl?易被内部浆体的水化产物重新吸附，对总体扩散进程影响较小。

Abstract:

This study investigated the diffusion of Cl? and SO?2? in cement paste under composite salt environments. For ordinary Portland cement paste, SO?2? in composite chloride solution initially inhibit chloride diffusion but subsequently enhance it over time. In composite chloride-sulfate solution, SO?2? persistently suppresses Cl? migration, though this inhibitory effect diminishes with prolonged exposure. Ordinary Portland cement paste exhibits a relatively weak adsorption capacity for Cl?. Consequently, free Cl? released under SO?2? attack diffuse more readily into the paste interior, significantly influencing the overall chloride diffusion process. At 180 days, the free Cl? diffusion coefficients for slag-cement paste were measured as 0.96, 0.81, and 0.77×10?12 m2/s in chloride, composite chloride and chloride-sulfate solutions, respectively. Slag-cement paste demonstrates strong adsorption capacity for Cl?. Free Cl? released from the superficial paste are readily re-adsorbed by the hydration products of inner paste, resulting in a comparatively minor impact on the overall diffusion process.