Valorization of non-conventional fly ashes in eco-efficient cements

Abstract

The aim of this project was to evaluate the potential of coal fly ash coming from a spreader stoker power plant (Reunion Island) to be used in cement-based materials. Actually this fly ash cannot be considered equivalent to pulverised coal fly ash regulated by EN 450-1, but its reuse could represent a real progress for the sustainable development of the island. This feasibility study is divided into three parts: 1? characterization of raw and treated fly ashes, 2- evaluation of the activity of the ashes in cement-based materials, and 3- fabrication of laboratory CEM II containing treated fly ashes. The results show that spreader stoker fly ash has properties similar to those of standard fly ash, except for the high unburned carbon content. The pozzolanic activity of raw and treated ashes is notable, leading to high strength activity indexes. However, rheological properties and setting time delays still need to be assessed. Laboratory CEM II cements made using the treated ashes gave superior mechanical performance when compared to CEM II containing typical constituents (clinker and natural pozzolana) usually found in Reunion Island