氯离子条件下矿物掺合料混凝土的电化学阻抗谱研究

摘要

对浸泡于清水和盐水中不同矿物掺合料的混凝土进行了电化学阻抗谱试验，分析了氯离子条件和矿物掺合料掺量对混凝土阻抗参数的影响。研究表明：在相同矿物掺量的条件下，浸泡于盐水中混凝土试块的孔溶液电阻、水化电子进行电荷传递的电阻、扩散阻抗系数均小于浸泡于清水中的试块，双电层电容大于浸泡于清水中的试块，常相角指数基本相同，说明浸泡于盐水中的混凝土，氯离子扩散进入混凝土增加了孔溶液和C-S-H凝胶的自由离子浓度，减小了孔溶液电解质的电阻和自由电荷在混凝土孔结构中的扩散阻力，而氯离子的存在对混凝土的孔结构特征影响不明显；在相同浸泡条件下，随着矿物掺量的增加，混凝土的阻抗参数孔溶液电阻、水化电子进行电荷传递的电阻、扩散阻抗系数和常相角指数呈增大趋势，双电层电容基本不变，说明矿物掺合料降低混凝土孔隙率，提高了混凝土密实度。%Electrochemical impedance spectroscopy tests were made to study the properties of concrete with the different mineral admixtures and immerged in fresh water and salt water,and the effect of chloride ions and mineral admixtures on the impedance parameters of concrete was analyzed.The results showed that,in the case of same admixtures amount,the impedance parameters,such as resistance of pore solution,resistance to transfer the hydrated electron,coefficient of diffusion impedance of concrete in salt water are smaller than those in fresh water,while the electric double layer capacitor of concrete in salt water was greater and the phase angle index was substantially constant,indicating that the chloride ions diffused into the concrete in salt water and increase the free ion concentration in pore solution and C-S-H gel and reducing the resistance of pore solution electrolyte and the diffusion resistance of free charge.Constant of phase angle index showed chloride ions had no obvious influence on the pore structure of concrete.In the case of same immersion condition,with the increase of mineral admixture content,the resistance of pore solution,resistance to transfer the hydrated electron, coefficient of diffusion impedance of concrete and phase angle index increase,while the electric double layer capacitor was substantially constant,indicating that the total porosity of concrete decreased and compaction of concrete enhanced by added mineral admixture.