混凝土中几种无机相对钢筋腐蚀的影响

用CaCO3、SiO2、Al2O3和Fe2O3为原料,通过高温固相反应,分别制备了组成单一的无机相粉体C3-S2、C3-A1和C4-A1-F1,以此来模拟混凝土无机相的主要成分。这3种粉体被分别浸泡到含有氯离子的混凝土孔隙模拟溶液中。针对浸泡实验的固液共存体系,分别做了钢筋的极化曲线测试、溶液相的氯离子浓度测试以及过滤产物的XRD晶相分析。分析结果表明,无机相粉体对钢筋起到减缓腐蚀的作用;溶液相中氯离子浓度随时间的延长均呈下降趋势,其中C3-A1和C4-A1-F1粉体对自由氯离子都有很强的结合能力;C3-A1和C4-A1-F1粉体的过滤产物中均发现了Friedel盐相(Ca2Al(OH)6Cl.2H2O),而C3-S2粉体的过滤产物中没有发现含有氯离子的产物晶体相,表明C3-A1和C4-A1-F1粉体模拟的铝酸钙(C3A)通过离子交换结合氯离子,而C3-S2粉体模拟的C-S-H凝胶相则通过物理吸附结合氯离子。

Influence of the inorganic phases present in concretes on corrosion of steel rebars

Inorganic powders C3-S2,C3-A1 and C4-A1-F1 were synthesized by high-temperature solid-state reac-tions,using CaCO_3,SiO_2,AL_2O_3 and Fe_2O_3 as raw materials,in order to simulate the inorganic phases present in concrete.The three inorganic powders were separately immersed in simulated concrete pore solution.Potentiody-namic polarization measurements,chloride ion concentration monitoring tests and XRD crystallography analysis were carried out.The results showed that the powders inhibited corrosion of steel rebar.In all three solid-liquid systems,the chloride ion concentrations decreased with increase of immersion time,and both C3-A1 and C4-A1-F1 powders possessed a strong capability to bind free chloride ions.Friedel's salt(Ca_2Al(OH)_6CL·2H_2O)was found in the percolation residues of the solutions containing C3-A1 and C4-A1-F1 powders,which was the result of calcium alu-minate(C_3A)binding chlorides through ion exchange,while no Friedel's salt was found in the percolation residue of the solution containing C3-S2 powder.This clearly suggests that calcium aluminate,can bind chloride ions strongly through ion exchange,and C-S-H gel can only bind chloride ions weakly through physical adsorption.