1 Procedure of EDTA
A typical chemical reaction of a slag could be like the following [NIST, D.P Bentz],
C7.88S7.39M3A + 2.6CH + bH → 7.39C1.42SHmA0.046 + 0.66M4.6AHd
C=CaO, S=SiO2, M=MgO, A=Al2 O3, CH=Ca(OH)2, H=H2O.
The method EDTA (Ethylenediaminetetraacetic acid) has been described by Erntroy [Erntry, 1987]. The following is a short description of the method.
Although it is somewhat difficult to measure the reaction degree of slag in slag blended cement comparing with the case in Portland cement, many researchers performed experiments on this field. A large body of literature can be found on the kinetics of Portland cement/slag blends.
Based on the modification of Takashima’s salicylic acid extraction method, Taylor collected some researchers’ data on the reaction degree of slag, as is showed in Table 1.
The reaction degree of slag in blended cement is difficult to measure using those methods which are successfully applied for Portland cement. Demoulian et al. described a method based on extraction of the constituents other than unreacted slag with a reagent based on Ethylene Diamine Tetraacetic Acid (EDTA), finding it effective for determining reaction degree of slag in unhydrated blended cements.