Radiological, Leaching, and Mechanical Properties of Cocombustion Fly Ash in Cements

AbstractWastes are used increasingly as construction materials to make the building industry more sustainable. In this regard, the European standards indicate the characteristics to be met by fly ashes used as cement replacement for the concrete manufacturing; such requirements dictate that the fly ash must not contain dangerous substances or to emit radiation. However, the tests to be performed are not indicated, nor are the maximum limits that cannot be exceeded. In this study, two different fly ashes are analyzed, one of which is obtained from the traditional coal combustion and the other from the cofiring of 70% by weight of petroleum coke and 30% of coal. Several mortar mixes with different compositions were manufactured, and chemical, physical, mechanical, leaching, and radiological tests were carried out on them. Both ashes satisfy the normative requirements about their chemical properties, volume stability, and setting time. The compressive strength of the cocombustion ash mortars was lower than those made with coal ash, although they showed a high strength activity comparable to that obtained for portland cement, in compositions up to 20%. Cements with cocombustion ashes as additive have not presented leaching nor radiological problems with regard to standards and recommendations.