Repassivation of steel in carbonated concrete induced by cathodic protection

The paper discusses the peculiarities of cathodic protection applied to steel in carbonated concrete, which are strictly connected to the production of alkalinity at the steel surface. Results of a research on the application of cathodic protection to specimens with steel bars in carbonated concrete are discussed. A thin layer of concrete was realkalized within a period of 4–5 months by applying a current density of 10 mA/m² and steel could repassivate even in the presence of small contents of chlorides. A lower current density of 5 mA/m² could only maintain steel passive when the concrete in the vicinity of the steel had been previously realkalized through the application of a start‐up current density of 70 mA/m² for one month. Protection mechanisms are investigated and design of cathodic protection of steel in carbonated concrete is outlined. The possibility of obtaining protection on deeper rebars is also considered.     

聚氯乙烯多乙烯胺树脂催化合成l-碘戊烷及其催化原理

本文报道了聚氯乙烯多乙烯胺(PVC-PP)树脂催化合成1-碘戊烷并简述了PVC-PP树脂的三相催化机理。     

Development of corrosion sensors for monitoring steel‐corroding agents in reinforced concrete structures

Corrosion sensors were devised to develop a system whereby the depth of chloride permeation from concrete surfaces can be monitored non‐destructively on a real‐time basis using such sensors embedded in cover concrete of reinforced concrete structures. The proposed corrosion sensors were subjected to accelerated corrosion in NaCl solutions, mortar specimens intrinsically containing chlorides, and mortar specimens impregnated with chloride solutions, while recording the changes in the resistance readings. The resistance of sensors increased as the degree of corrosion increased. The time to the first change in the resistance decreased and the corrosion degree and resistance increased as the chloride concentration increased and as the distance from mortar surfaces decreased. It was therefore confirmed that the corrosion sensors are capable of monitoring the depth of chloride permeation with sufficient accuracy.