Effects of accelerators on concrete containing electric arc furnace dust

The incorporation of electric arc furnace dust into concrete at substantial levels of addition is known to be associated with excessive retardation of cement hydration owing to the presence of high levels of zinc and other heavy metals in the material. The research described herein was aimed at evaluating the potential for counteracting this by controlled addition of chloride-free accelerating admixtures to concrete containing electric arc furnace dust. Calcium nitrite and calcium formate were both found to be effective in accelerating the hardening process but ineffective in reducing the setting time. They were also found to improve the workability of concrete containing a substantial level of electric arc furnace dust. The role of the accelerators as a means of countering the effect of electric arc furnace dust in delaying formation of portlandite and other cement hydration products was elucidated by thermal analysis techniques.