Effect of boron waste and boric acid addition on the production of low energy belite cement

The effect of boron oxide addition on the production of low energy belite cements has been investigated. Three types of clinkers were prepared with 1.5 wt.% (BC_BA1.5) boric acid, and 1.0 wt.% (BC_BW1) and 6.5 wt.% (BC_BW6.5) boron waste addition. The design of the raw mixtures was based on modified Bogue equations. According to the free lime content and the evolution of the microstructure of the clinkers, firing was performed at 1330 °C, 1350 °C and 1310 °C for BC_BA1.5, BC_BW1 and BC_BW6.5, respectively. Boron addition favored the reduction of the clinkering temperature as well as the stabilization of upper belite polymorphs. According to the present results, late compressive strength development of belite cements depends mainly on the crystal type rather than on the content of belite in the clinker. The results indicate that controlled quantities of boron oxide can be beneficial in the production of belite cement.