⁵⁷Fe Mössbauer study of cement water-degradation

The structural evolution of iron during cement paste degradation is studied. An increased concentration of iron has been observed in the surface layer formed when cement paste comes into contact with an aggressive solution. While C₄AF and C₃(A, F)SH₄ are little affected by leaching, the calcium silicate hydrates (CSH) become richer in trivalent iron on the surface. The latter replaces the labile and non-labile calcium of the structure, the labile form being predominant.