探討利用電化學再鹼化技術修復火害後鋼筋混凝土的效果

Study on the Efficiency of Electrochemical Realkalisation to Repair of Fire-Damaged Reinforced Concrete

本研究探討利用電化學再鹼化技術修復火害鋼筋混凝土的效果。本實驗使用兩種試件包括普通強度試件及高強度試件的火害鋼筋混凝土。在試驗過程中，通過直流變壓器對試件通電，經不同電流時間 (1至 7天)、外加電流密度 (0.5 A/㎡、1.0 A/㎡ 及 1.5 A/㎡)，及不同的電解液 (Na2CO3、Na2SiO3 及 MgCl2)後，然後測定電解液中所產生測點電勢及電阻。由結果發現普通強度試件或高強度試件，三種的電解質皆隨著通電時間增至 7天，測點電勢逐漸降低，而電阻增加。於通電時間 7天時，普通強度的試件於外加電流密度保持在1.0 A/㎡左右即可，而高強度試件的外加電流密度可以適當增大至1.5 A/㎡。在相同的外加電流密度和通電時間下，比較Na2CO3及MgCl2對試件的再鹼化修復後，前者有較低電流測點電勢及較高的電阻。兩種電解質於通電時間 7天，外加電流強度以 1.0 A/㎡ 及1.5 A/㎡條件，分別對普通試件及高強度試件皆可有效恢復火害後鋼筋混凝土的鹼性環境。

This study investigated the efficiency of an electrochemical realkalisation technique to repair fire-damaged reinforced concrete. The two experimental specimens used were a normal-strength specimen and a high-strength specimen of fire-damaged reinforced concrete. In the experiment, an electric current was passed through the two specimens via the DC transformer, for different power-on times (1-7 days), current densities (0.5 A / m2, 1.0 A / m2 and 1.5 A / m2), and different electrolytes (Na2CO3, Na2SiO3 and MgCl2). Then electrolyte potential and current resistance for the anolyte were measured. The results showed current density of anolyte at approximately 1.0 A/㎡for both normal strength specimen and 1.5 A/㎡for high strength specimen show significant repair after 7 days of electrochemical realkalisation. The electrolyte potential of anolyte showed gradual reduction, and the resistance increased in the area near the surface of the concrete. Current density for the normal strength specimen was maintained at approximately 1.0 A/㎡, while the high strength specimen was held at 1.5 A/㎡. Comparing Na2CO3 and MgCl2 of the specimens after realkalisation, the former has a lower current potential and higher current resistance in the anolyte, at the same current density and powered time. Under previous conditions, two electrolytes can restore an alkaline environment to fire-damaged reinforced concrete after electrochemical realkalisation.