Development of cementless ultra-high performance fly ash composite (UHPFC) using nucleated pozzolanic reaction of low Ca fly ash. (September 2022)

• Record Type: Journal Article
• Authors: Kang, Sung-Hoon; Kang, Hyunuk; Lee, Nankyoung; Kwon, Yang-Hee; Moon, Juhyuk
• Is Part Of: Cement & concrete composites. Volume 132(2022)
• Publication Date: 2022-09
• Subjects: Ultra-high performance fly ash composite -- Low-calcium fly ash -- Reactivity -- Pozzolanic reaction -- Steam curing -- Filler effect; Composite-reinforced concrete -- Periodicals; Concrete -- Periodicals; Composite materials -- Periodicals; Composites de ciment -- Périodiques; Béton -- Périodiques; Composites -- Périodiques; Béton léger -- Périodiques; Cement composites; Composite materials; Composite-reinforced concrete; Concrete; Lightweight concrete; Periodicals; Electronic journals; 620.135
• DOI: 10.1016/j.cemconcomp.2022.104650
• Languages: English
• ISSNs: 0958-9465

Abstract

Abstract: This study developed ultra-high performance fly ash composite (UHPFC) by enhancing the pozzolanic reactivity of low-calcium fly ash (FA). Although it did not include Portland cement, the composite exhibited outstanding performance in workability, mechanical properties, and strength development. At room temperature (20 °C), the hydrated lime-activated FA containing silica fume showed a distinct acceleration period. Moreover, 3 days of steam curing at 60 °C guaranteed its final strength (∼110 MPa) before 7 days because of the synergistic effect between the ultrafine filler and steam curing. At 60 °C, the reactivity of FA was dramatically improved only when nucleation sites were provided by silica fume. Furthermore, increasing the curing temperature reciprocally affected FA and silica fume in the reaction; while FA was a leading participant in the pozzolanic reaction, silica fume mostly played a role as a physical filler, providing the nucleation site for reaction products.