Effect of prefiring and firing dwell times on the properties of artificial lightweight aggregates

• Expansion of artificial aggregates largely depends on the prefiring dwell time.
• Shorter prefiring and firing times produce less dense artificial aggregates.
• Prefiring and firing times affect the formation of a vitrified external layer.
• Prefiring and firing times affect the formation of longer internal pores.

The effects of the prefiring and firing dwell times on the chemical, physical and microstructural properties of artificial lightweight aggregates (LWAs) produced from mining and industrial waste with a tubular rotary kiln were determined. It was observed that 1.5 and 3 min of prefiring and firing dwell times, respectively, were more adequate than 5 and 4 min for producing less dense artificial aggregates (0.98 g/cm3 vs 1.64 g/cm3). The LWAs manufactured with shorter dwell times could be used in gardening and horticulture, geotechnical applications and/or as insulation materials. LWAs manufactured with longer dwell times could also be used for insulating lightweight concrete and/or prefabricated lightweight structures.