Oil cracking waste catalyst as an active pozzolanic material for superplasticized mortars

Superplasticized mortars containing waste catalyst (EPcat) have been characterized. This waste catalyst comes from catalytic crackers of oil companies. It consists mainly of silicon oxide and aluminum oxide, and shows some amorphous structure. Test results indicate that more superplasticizer or water is required for maintaining the workability of mortars incorporating EPcat. Nevertheless, mortars with EPcat exhibit greater compressive strength than those without. The strength improvement could be attributed to high pozzolanic activity of the waste catalyst. One evidence is that earlier temperature rise was observed in EPcat mortars during hydration than plain ones. Besides, the microstructure analysis indicates that both ettringite and monosulfoaluminate were produced in the early curing period of EPcat mortars. These confirm that EPcat could accelerate the cement hydration by inducing a pozzolanic reaction between the catalyst and calcium hydroxide, the cement hydrated product. (C) 2001 Elsevier Science Ltd. All rights reserved.