Effects of fly ash properties on characteristics of cold-bonded fly ash lightweight aggregates

The study presented herein provides a new insight into the effects of physical and chemical properties of the fly ash on the characteristics of the cold-bonded fly ash lightweight aggregates. LWAs were manufactured through the cold-bonding pelletization of two fly ashes differing in their physical and chemical properties. Moreover, one type of the LWAs was surface treated by water glass. The produced fly ash aggregates were then examined by means of ESEM micrograph, EDX spectrum, and XRD pattern to resolve the microstructural and the mineralogical characteristics of the LWAs. The findings of the study revealed that the fly ash with higher specific surface and with lower CaO content yielded higher strength LWAs. Furthermore, the surface treatment with water glass provided a marked increase in the aggregate strength and a reduction in the water absorption. The LWCs made with such LWAs had a compressive strength of as high as 60 MPa.