Investigating the role of reactive silica in the hydration mechanisms of high-calcium fly ash/cement systems

Antiohos, S; Tsimas, S

dc.contributor.author	Antiohos, S	en
dc.contributor.author	Tsimas, S	en
dc.date.accessioned	2014-03-01T01:22:32Z
dc.date.available	2014-03-01T01:22:32Z
dc.date.issued	2005	en
dc.identifier.issn	0958-9465	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/16610
dc.subject	Active silica	en
dc.subject	Glass	en
dc.subject	High-lime fly ash	en
dc.subject	Hydration kinetics	en
dc.subject	Performance prediction	en
dc.subject.classification	Construction & Building Technology	en
dc.subject.classification	Materials Science, Composites	en
dc.subject.other	Calcium	en
dc.subject.other	Fly ash	en
dc.subject.other	Glass	en
dc.subject.other	Hydration	en
dc.subject.other	Portland cement	en
dc.subject.other	Power plants	en
dc.subject.other	Reaction kinetics	en
dc.subject.other	Silica	en
dc.subject.other	Active silica	en
dc.subject.other	High-lime fly ash	en
dc.subject.other	Hydration kinetics	en
dc.subject.other	Performance prediction	en
dc.subject.other	Pozzolan	en
dc.title	Investigating the role of reactive silica in the hydration mechanisms of high-calcium fly ash/cement systems	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.cemconcomp.2004.02.004	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.cemconcomp.2004.02.004	en
heal.language	English	en
heal.publicationDate	2005	en
heal.abstract	High-calcium fly ashes (ASTM Class C) are being widely used as a replacement of cement in normal and high strength concrete. In Greece such fly ashes represent the majority of the industrial by-products that possess pozzolanic properties. Even thought the contribution of factors, such as fineness and water/binder ratio, on the performance of fly ash/cement (FC) systems has been a common research topic, little work has been done on examining whether and to what extent reactive silica of fly ashes affects the mechanisms occurring during their hydration. The work presented herein describes a laboratory scale study on the influence of active silica of two high-lime fly ashes on their behavior during hydration. Volumes up to 30% of Greek high-calcium fly ashes, diversified both on their reactive silica content and silicon/calcium oxides ratio, were used to prepare mixes with Portland cement. The new blends were examined in terms of compressive strength, remaining calcium hydroxide, generation of hydration products and microstructural development. It was found that soluble silica of fly ashes holds a predominant role especially after the first month of the hardening process. At this stage, silica is increasingly dissolved in the matrix forming additional cementitious compounds with binding properties, principally a second generation C-S-H. The rate however, that fly ashes react in FC systems seems to be independent of their active silica content. indicating that additional factors such as glass content and fineness should be taken into account for predicting the contribution of fly ashes in the final performance of pozzolanic cementitious systems. (C) 2004 Elsevier Ltd. All rights reserved.	en
heal.publisher	ELSEVIER SCI LTD	en
heal.journalName	Cement and Concrete Composites	en
dc.identifier.doi	10.1016/j.cemconcomp.2004.02.004	en
dc.identifier.isi	ISI:000226478000004	en
dc.identifier.volume	27	en
dc.identifier.issue	2	en
dc.identifier.spage	171	en
dc.identifier.epage	181	en