Synergistic effect of RHA and FCW in alkali-aggregate reaction mitigation

• Autor(a) principal: Guillante,Patrícia
• Data de Publicação: 2019
• Outros Autores: Abreu,Aguida Gomes de, Kulakowski,Marlova Piva, Mancio,Maurício, Kazmierczak,Claudio de Souza
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Ambiente construído (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1678-86212019000200007
• topic: Rice Husk Ash; Fired Clay Brick Waste; Alkali-Aggregate Reaction

Abstract Pozzolans rich in silica, such as Rice Husk Ash (RHA), contribute to compressive strength gain but at the same time might increase alkali-aggregate reaction (AAR) in mortar mixtures. Pozzolans that have aluminates, such as Fired Clay Brick Waste (FCW), can be efficient to mitigate AAR but tend to lead to a slower compressive strength development. The association of different types of pozzolans, however, may result in a synergistic effect, compensating individual deficiencies. This paper presents a study of mixtures containing RHA, FCW and these two materials combined, aiming to obtain benefits in the mechanical behavior and in the durability regarding AAR. A substitution rate of 20% Portland cement by pozzolanic material was used. Through accelerated AAR tests and compressive strength measurements, it was found that while RHA is considered harmful to AAR - even when using an innocuous aggregate - FCW presents benefits, also avoiding this deleterious effect when combined with RHA. The same occurs in the compressive strength development, where RHA compensates a small loss of compressive strength associated with the use of FWC alone.