Rietveld Quantitative Stability of Portland Blast Furnace Slag Cement Between Internal and External Standard Methods

The internal and external standard (G-factor) methods were applied to Rietveld/XRD quantitative analysis of Portland blast furnace slag cement using X'Pert Highscore Plus and GSAS-EXPGUI software. The Rietveld quantitative result derived from G-factor calculation and application was compared by internal standard methodology, which was employed by separately adding 20 and 50 % (weight percentage) of SiO2. The results show that the quantitations obtained by both of the above independent methods are almost consistent. In addition, the quantitative difference of most crystalline phases are less than 1 % except C(4)AF, about 1.2 %, while the amorphous determination has the quantitative difference of 2.1 %. Beside the careful sample preparation, proper XRD pattern collection, and satisfactory Rietveld refined procedure, the polished quartz rock used for mean G-factor calculation and the modified formula for amorphous calculation contributed to the Rietveld quantitative stability and reasonability. The formula based on amorphous quantification by internal standard was expressed as W-Amor = 1-(W-S(1-W'(S(PS+Sta))))/((W'(S(PS+Sta))-W'(S(PS)))(1-W-S)).