Hardening effects of conversion

Calcium aluminate cements harden rapidly as soon as the massive precipitation of hydrates begins. This may be attributed to the fact that, unlike those of Portland cement, the major hydration products are crystalline. Relatively high proportions of water are taken up in the hydration reactions, the theoretical w/c ratios needed for complete hydration of CA being 1.14, 0.63 and 0.46 for the formation of CAHj, CjAHg -F AHj and CjAH -F 2AHj, respectively. For this reason, and also because of the rapid heat 

Conversion is of only minor importance for the use of calcium aluminate cements in refractory applications and in mixes with Portland cement such as those described in Section 10.1.10. 

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