Estimates of cement compositions were made using a modified Bogue calculation described by Taylor [22]. Chemical data for these analyses were taken from the Iowa State University testing results provided in the Iowa Department of Transportation materials database. As data were not available, assumptions for free lime (0.3 %) were made for all estimates. These data show that, if one considers total silicates as a group, cement compositions appear generally uniform across the job interval. Variations in the silicate phase fractions may reflect deviations of the free lime content from that assumed in the calculations (Figure 7), errors in sampling, and analysis. These data were later used in conjunction with the mix design to estimate the potential volume of ettringite formation to test the hypothesis of excess ettringite formation. Data were not available to allow matching of cement analyses with pavement locations.
| C3S | C2S | C3 A | C4AF | Free Lime | Periclase | Gypsum | K2 SO4 | Na2SO 4 | Ckr.CaSO4 | |
| Avg. | 51.2 | 28.0 | 4.8 | 7.4 | 0.3 | 1.5 | 5.7 | 1.0 | 0.0 | 0.0 |
| Stdev. | 18.7 | 20.4 | 1.4 | 0.5 | 0.0 | 0.3 | 0.5 | 0.0 | 0.1 | 0.0 |
| C3S | C2S | C3 A | C4AF | Free Lime | Periclase | Gypsum | K 2SO4 | Na2SO 4 | Ckr.CaSO4 | |
| Avg. | 45.7 | 35.2 | 3.4 | 8.3 | 0.3 | 1.8 | 4.4 | 0.9 | 0.2 | 0.0 |
| Stdev. | 9.4 | 10.3 | 1.3 | 0.8 | 0.0 | 0.3 | 0.6 | 0.1 | 0.1 | 0.1 |
Figure 7. Cement compositions, expressed as mass percent, from chemical analyses from the Iowa DOT database and using a modified Bogue calculation described in Taylor [22]. The y-axis has been expanded to more clearly illustrate total silicates and other phases.