Effect of nitrite intercalated Mg-Al layered double hydroxides on mortar durability under Cl−and SO_(4)^(2-) coexisting environment

氯盐和硫酸盐共存环境下插层亚硝酸根镁铝水滑石对砂浆耐久性的影响

The aim of this paper is to investigate the effect of nitrite intercalated Mg-Al layered double hydroxides(Mg-Al LDH-NO_(2))on mortar durability under the coexisting environment of Cl−and SO_(4)^(2-).Cl−and SO_(4)^(2-) binding properties of Mg-Al LDH-NO_(2) in simulated concrete pore solutions,Cl−and SO_(4)^(2-) diffusion properties of mortars with Mg-Al LDHNO 2 were examined.The steel corrosion and resistance of mortar against SO_(4)^(2-) attack were also evaluated.The results indicate that Mg-Al LDH-NO_(2) can effectively adsorb the Cl−and SO_(4)^(2-) in simulated concrete pore solution,and inhibit the diffusion of Cl−and SO_(4)^(2-) into cement mortars.The presence of SO_(4)^(2-) can greatly affect the uptake amount of Cl−,and there is a coupled effect of Cl−and SO_(4)^(2-) on their penetration into mortar specimens.In addition,Mg-Al LDH-NO_(2) can greatly upgrade the resistance of mortars against SO_(4)^(2-) attack and well prevent the steel from corrosion.However,Cl−will aggravate the SO_(4)^(2-) attack and SO_(4)^(2-) can initially decrease and then increase the steel corrosion.

本文研究了插层亚硝酸根镁铝水滑石在模拟混凝土孔溶液中的氯离子和硫酸根离子结合特性和在砂浆中对氯离子和硫酸根离子传输以及钢筋腐蚀和硫酸盐侵蚀的影响。结果表明,插层亚硝酸镁铝水滑石能有效吸附模拟混凝土孔溶液中的氯离子和硫酸根离子,并且抑制氯离子和硫酸根离子在水泥砂浆中的传输。环境中硫酸根离子的存在会极大地影响插层亚硝酸根镁铝水滑石对氯离子的吸附,并且氯离子和硫酸根在砂浆中的传输具有耦合作用。此外,插层亚硝酸根镁铝水滑石可以大大提高砂浆抗硫酸盐侵蚀的能力,并能很好地预防砂浆内钢筋发生腐蚀。但环境中氯盐的存在会加剧硫酸盐侵蚀,而硫酸盐的存在会先抑制后加剧砂浆内钢筋发生锈蚀。