Use of wastes of the sugar industry as pozzolana in lime-pozzolana binders: Study of the reaction

Mineralogical studies of different wastes of the sugar industry, mainly sug ar cane bagasse ash and sugar cane straw ash, have shown that such by-produ cts are likely to be pozzolanic. Their use in lime-pozzolana binders could become an interesting alternative for developing countries. This paper pres ents a study that was aimed at monitoring the reaction between lime and was tes of the sugar industry having pozzolanic properties by evaluating 1) con tent of calcium hydroxide, dependent on time; 2) development of the pore st ructure, dependent on time; 3) study of the reaction products at different stages; and 4) mechanical properties of hardened pastes. The presence of ca lcium hydroxide was confirmed by x-ray diffraction analysis and thermogravi metic analysis of powder from samples of hydrated lime-pozzolana pastes. Th e reaction products in hydrated pastes were observed in a scanning electron microscope, and the pore structure was assessed using a mercury intrusion porosimeter: The results of the study show that sugar cane bagasse ash does not act like a reactive pozzolana, mainly due to the presence of unburned material and carbon, whereas sugar cane straw ash shows good gozzolanic act ivity comparable to that of rice husk ash. (C) 1998 Elsevier Science Ltd.