The Influence of CO2-Cured Incinerated Waste Fly Ash on the Performance of Reactive Powder Concrete

Abstract

Incinerated waste fly ash is a toxic solid, which can cause serious harm to the environment. CO2-cured incinerated waste fly ash may be useful in decreasing the toxicity of waste fly ash and improving the corresponding mechanical properties of cement-based material with incinerated waste fly ash. Meanwhile, this technology can play a certain role in reducing the content of CO2 in the atmosphere. In this study, the influence of CO2-cured incinerated waste fly ash on the rheological parameters (the slump flow and plastic viscosity) and the setting time of fresh reactive powder cement concrete (RPC) is investigated. The flexural and compressive strengths of hardened RPC standard cured for 1 day, 3 days, and 28 days are measured. The leached amounts of Cr and Zn immersed in water for 6 months are measured. The scanning electron microscope photos, thermogravimetric analysis curves, and mercury intrusion curves are obtained. Our results show that the slump flow, the setting time, and the flexural and compressive strengths increased, and the plastic viscosity decreased by adding the waste fly ash with the maximum varying rates of 12.1%, 41.7%, 41.3%, and 61.2%, respectively. CO2 curing on the waste fly ash can increase the setting time and the flexural and compressive strengths with the maximum varying rates of 19.2%, 13.1%, and 14.2%. The effect of CO2-cured waste fly ash on the mechanical strengths of RPC is quite limited.