Friedel’s Salt and Hydrotalcite – Layered Double Hydroxides and the Protection against Chloride Induced Corrosion

Abstract

This paper discusses some aspects of corrosion protection that fly ash and GGBFS offer to steel reinforcement in concrete. It focuses on the formation of two types of Layered Double Hydroxides (LDH’s). These are Friedel’s salt and Hydrotalcite. While Friedel’s salt is known to form in fly ash blends, the authors support the evidence of hydrotalcite formation in GGBFS blends as a result of the magnesium content in the slag. The paper discusses the corrosion protection performance of GGBFS concrete and compares it to that of fly ash concrete. The paper shows the superior advantage of including GGBFS for corrosion protection. The authors explored the probable reasons for this significant advantage and relate it to the formation of hydrotalcite in GGBFS concretes.