Establishment of electrodeposition technology for rehabilitation of concrete with drying shrinkage crack

(1)采用电沉积技术可以封闭钢筋混凝土的干燥收缩裂缝。(2)电沉积技术可以降低干缩裂缝钢筋混凝土的质量渗透性。例如，在充电1天后，开裂部分的透水系数变得小于未开裂部分的透水系数。在3天后，开裂部位的碳化深度比未开裂部位的碳化深度要小。(3)采用含醋酸镁的外溶液型，可以保持外溶液的pH值不变，从而提高裂缝的闭合能力和抗碳化能力。(4)从裂缝闭合和抗碳化性能的角度考虑，本研究中的最佳电沉积条件为：外加醋酸镁溶液，溶液浓度：0.1 mol/1，电流密度：1.0 A/m^2。（5）电沉积物可在砂浆孔隙内（距砂浆表面1 cm）存款，减小砂浆的孔容。(6)由于电沉积的表面改善能力，充电1天后的非开裂部分的碳化深度变为电沉积前的一半。(7)电沉积增强混凝土的透水系数在干湿反复作用后仍保持不变。(8)电沉积物与砂浆的粘结强度最大，为1.82N/mm^2，与砂浆的抗拉强度相当。

(1) Using the electrodeposition technology, the drying shrinkage cracks of reintorced concrete could be closed.(2) Electrodeposition technology could reduce mass permeability of reinforced concrete with drying shrinkage crack. For example, water permeability coefficient of cracking part became smaller than that of non- cracking part after l day charging. And carbonation depth of cracking part became shorter than that of non-cracking part after 3 days charging.(3) Using external solution type containing magnesium acetate, the pH of external solution could be kept constant, followed with the improvement of crack closure and carbonation resistance.(4) From the view point of crack closure and carbonation resistance, the best electrodeposition conditions investigated in this study were as follows : External Solution magnesium acetate, Solution Concentration : 0.1 mol/1, Current Density : 1.0 A/m^2(5) Electrodeposits could deposit inside the pore of mortar(1 cm deep from the surface), which reduced pore volume of mortar.(6) Due to the surface improvement ability of e1ectrodeposition, the carbonation depth at the non-cracking part after 1 day charging became half of that before applying electrodeposition.(7) The water permeability coefficient of electrodeposited rcinforced concrete was constant even after suffering from the dry and wet repetition.(8) The adhesive strength of electrodeposition to mortar maximized at 1.82N/mm^2, which was equivalent to the tensile strength of the mortar.