ANALYSIS OF THE CHLORIDE BINDING ABILITY OF CEMENTS

Abstract

We examined the binding process of NaCI penetrating into hardened cements from outer source through Hungarian manufactured cements representing both general and special fields of application. These types are the following: 450 Rpc, S 54, 350 ppc 20 and 250 kspc 60. We observed the effect of chlorides entering cements (between 1-28 and 28-56 days) by thermal analysis and X-ray diffraction spectroscopy. X-ray diffraction analysis proved that the chloride ion of NaCI is bound by C₃A and C₄AF in the form C₃A· CaCl₂ · H₁₀ containing ferrite. Chloro-aluminate-hydrates were formed not only in the first phase of hydration but in the hardened cement as well by the substitution of anions of the present AFm phases: C₃A· CaS0₄· H₁₂,, C₃A· Ca(OH)₂ . H₁₂, C₃A· CaC0₃· H₁₁. Neither X-ray diffraction nor thermal analysis investigations detected any chlorous calcium-silicate-hydrates.