Using pozzolanic components in concrete mixtures has several considerable benefits. However, the description of understanding on many of the properties of such concretes and structures is still doubtful, especially concerning the steel corrosion protection capacity. As generally known, the amount of calcium hydroxide [Ca(OH)(2)] contained in a concrete sample plays an important role for steel passivity and corrosion resistance, especially the buffering capacity subjected to depassivating phenomena. When cement in a concrete mixture is replaced by pozzolan, the total lime content in the concrete decreases, which may lead to a faster and higher carbonation and corrosion rate of the embedded steel reinforcement. The study proposes a new appropriate testing method for investigating small amounts of hydroxide content in cement paste, mortar applied, or concrete, especially for pozzolanic cementing materials. The new chemical procedure is conducted on several samples, and the results are compared with those of other well-known methods, namely, DTA and Franke method. The results show that the new method gives results comparable to the result from DTA analysis. In case of very low Ca(OH)(2) content analysis of artificial sample containing pozzolanic additions, only the proposed new analyzing method yields precise reliable results. (C) 2003 Elsevier Ltd. All rights reserved.
