Influence of mineralogical composition on the properties of lightweight aggregate

When sintering artificial lightweight aggregate, rapid cooling will generate micro-cracks. The paper investigates the effect of MgO contents on the physical, chemical and microstructural properties of artificial lightweight aggregate prepared under natural cooling in the furnace (SC) and rapid cooling outside the furnace (RC). Results indicate that cordierite (2MgO center dot 2Al(2)O(3)center dot 5SiO(2)) starts forming in lightweight aggregate when MgO content reaches 2%, accompanied by a reduction in mullite. Cordierite has a better thermal-shock resistance and its presence minimizes the potential for micro-crack formation, thus decreasing water absorption under rapid cooling conditions for the 2% MgO system. (C) 2009 Elsevier Ltd. All rights reserved.