Application of encapsulated lightweight aggregate impregnated with sodium monofluorophosphate as a self-healing agent in blast furnace slag mortar

This paper studies the potential of using expanded clay lightweight aggregate impregnated with sodium monofluorophosphate (Na2FPO3) solution which is eventually encapsulated by a cement paste layer to produce a self-healing system in blast furnace slag cement mortars. It was found that the technique significantly improved the quality of the interfacial transition zone in mortars subjected to carbonation shrinkage. Consequently the frost salt scaling durability of blast furnace slag mortars was evidently promoted. The findings from ESEM and EDS studies showed that the healing mechanism would be due to the combination of treatment by Na2FPO3 solution and calcium hydroxide supplied from the cement paste coating layer

Electrochemical Measurements in Cement Extract Solutions on Reinforcing Steel, Previously Conditioned in Concrete

The corrosion behavior of reinforcing steel, previously embedded in concrete and maintained in conditions of corrosion and two regimes (conventional and pulse) of cathodic protection (CP), was characterized using electrochemical measurements in cement extract (CE) solutions of pH 12.6. The investigation aimed at determination of the properties of the product layers, previously formed on the steel surface. The study further allowed evaluation of the CP effectiveness in terms of steel surface oxidation/reduction behavior in the alkaline medium of CE. Based on the similar electrochemical behavior of protected specimens, it can be concluded that the pulse CP is as effective as the conventional CP regime. Moreover, the surface film, formed in pulse CP conditions appears to be more homogeneous and resistive, compared to the conventional CP regime.Delft University of Technolog