Properties and Microstructure of Eco-Cement Produced from Co-Sintered Washed Fly Ash and Waste Sludge

This study investigated the possibility of recycling washed fly ash, limestone sludge, stone sludge, and iron-oxide sludge in raw meal for producing Portland cement clinker. All of the major phase components of ordinary Portland cement (OPC)-C3S, C2S, C(3)A, and C(4)AF-were identified in each eco-cement clinker. The compressive strength development showed that the eco-cement pastes no contained washed fly ash was similar to commercial OPC products. The exothermic peak at 105 degrees C to 440 degrees C corresponded to the coordination change of C-S-H gel in the pastes during curing time. The TG/DTA curves showed that the weight loss of the eco-cement pastes no contained washed fly ash was higher than that of the eco-cement pastes contained 1% washed fly ash. The Q(0) (-70 ppm) species shifted to the Q(1) (-80 ppm) and Q(2) (-87 ppm) species during curing time. The degrees of hydration of the eco-cement pastes contained 2 to 4% washed fly ash were lower than that of the eco-cement pastes no contained washed fly ash. The results of the physicomechanical tests showed that adding the limestone sludge, stone sludge, and iron-oxide sludge did not negatively affect the quality of the produced cement. (C) 2016 American Institute of Chemical Engineers Environ Prog, 35: 764-771, 2016