Valuable utilization of spray dryer ash and its performance in structural concrete

Abstract

This research focuses on the valuable utilization of Spray Dryer Ash (SDA) and investigates its performance in concrete for structural and transportation applications. Based on the challenges associated with coal ash (including SDA) and the economic costs linked to cement production, this research seeks to provide an environmentally friendly and more cost effective concrete product by utilizing SDA in partial replacement of cement in concrete. Cement production is a rather expensive venture and yet there is an abundance of coal ash that is disposed of in landfills that could be utilized positively. The fineness and low carbon content properties of SDA/ Class C fly ash provide potential benefits of increased strength (compressive and bond) and durability (freeze-thaw and corrosion) when used in concrete. With the exception of high sulfur content, SDA exhibits very excellent properties that are closely related to Class C fly ash and Portland cement. The addition of Spray Dryer Ash in non-air entrained concrete provided a general increase in its strength. The compressive strength test results indicate that replacing proportions of cement with SDA would provide improved strength and a most cost effective solution. When utilized within optimal limits of 25-35% replacement, SDA presents reasonable benefits to compressive and bond strength. The utilization of SDA provided modest benefits when used in certain proportions and at the very least it did not seem to degrade the properties much. It produced a negligible effect on the freeze-thaw durability of the concrete while an increase in the SDA provided an increased corrosion resistance and a reduced corrosion rate in concrete. Based on the results of this research, SDA has great potential for its utilization as a structural material in transportation infrastructures.