Simultaneous refinement of X-ray diffraction patterns of multiple phases allows quantitative analysis using the following relationship, whose variables (aside from Z) are all refined in the fitting process:
| Wp = (Sp (ZMV)p) / (S [S (ZMV)]) | (1) |
where
Wp = the mass fraction of phase p,
S = the Rietveld scale factor,
Z = the number of formula units per unit cell,
M = the mass of the formula unit, and
V = the unit cell volume.
Initial estimates of the phase fractions were used to estimate the linear absorption coefficient of the mixture. A second quantitative estimate using a Brindley absorption correction, based upon a mean particle size of
1 µm, established the final analyses. Phase abundance estimates of polymorphs of specific phases, such as
-C2S and
-C2S or cubic and orthorhombic C3A were summed for comparison with the optical microscopy data.


Figure 7. A straight normal probability plot of the errors indicates their distribution is well approximated by a Gaussian.
| Table 2 Mass fraction (percent) by QXRD, RM 8486 optical data (OM), and round robin data (RR) following ASTM C 1356 [2]. QXRD analysis of nine vials (1-9) with two splits per vial (a, b), with each split analyzed in duplicate (1, 2). | |||||
|---|---|---|---|---|---|
| Alite | Belite | Ferrite | Aluminate | Periclase | |
|
1a1 |
56.4 |
21.5 |
13.8 |
3.9 |
4.3 |
| Table 3. Mass fraction (percent) by QXRD, RM 8487 optical data (OM), and round robin data (RR) following ASTM C 1356 [2]. QXRD analysis of nine vials (1-9) with two splits per vial (a, b), with each split analyzed in duplicate (1, 2). | ||||||
|---|---|---|---|---|---|---|
|
Alite |
Belite |
Ferrite |
Aluminate |
Arcanite |
Free Lime* |
|
1a1 |
74.7 |
11.2 |
4.3 |
8.3 |
0.6 |
|
* XRD data did not measure free lime as it was altered during sample preparation and storage.
| Table 4. Mass fraction (percent) by QXRD, RM 8488 optical data (OM), and round robin data (RR) following ASTM C 1356 [2]. QXRD analysis of nine vials (1-9) with two splits per vial (a, b), with each split analyzed in duplicate (1, 2). | ||||
|---|---|---|---|---|
|
Alite |
Belite |
Ferrite |
Aluminate |
|
1a1 |
67.2 |
14.8 |
14.3 |
3.7 |
| Table 5. RM Clinker QXRD Summary: 95 % Confidence Limits for the Mean (Mass Percent). | |||
|---|---|---|---|
| Limits | Lower | Mean | Upper |
| RM 8486 | |||
| Alite | 56.50 | 56.75 | 57.00 |
| Belite | 20.91 | 21.04 | 21.17 |
| Aluminate | 3.41 | 3.46 | 3.50 |
| Ferrite | 14.40 | 14.61 | 14.81 |
| Periclase | 4.07 | 4.13 | 4.20 |
| Limits | Lower | Mean | Upper |
| RM 8487 | |||
| Alite | 73.51 | 74.18 | 74.85 |
| Belite | 10.95 | 11.44 | 11.92 |
| Aluminate | 7.98 | 8.35 | 8.73 |
| Ferrite | 4.11 | 4.51 | 4.91 |
| Periclase | 0.77 | 0.91 | 1.05 |
| Limits | Lower | Mean | Upper |
| RM 8488 | |||
| Alite | 65.91 | 67.55 | 69.18 |
| Belite | 13.64 | 14.77 | 15.90 |
| Aluminate | 3.36 | 3.66 | 3.96 |
| Ferrite | 12.33 | 14.02 | 15.71 |