Influence of temperature on the hydration of blended cements

Author(s): B. Lothenbach, G. Le Saout
Paper category: Conference
Book title: Concrete Repair, Rehabilitation and Retrofitting III (ICCRRR)
Editor(s): M.G. Alexander, H.-D. Beushausen, F. Dehn, P. Moyo
Print ISBN: 978-0-415-89952-9
Publisher: Taylor & Francis Group
Pages: 517- 518
Total Pages: 2
Language: English

Abstract: 
Blending of Portland cement with silica-rich materials leads to changes in composition of the hydrated cement and of its pore solution. In blends rich in SiO₂ all the portlandite formed by the Portland cement reaction is consumed within a few weeks and the formation of more C-S-H with a lower Ca/Si ratio is observed. This leads to an increased binding of alkalis and lower hydroxide concentrations. With time as more SiO2 reacts monocarbonate and monosulfate are destabilised and in the very long term also ettringite. Higher temperatures increase the reactivity of both, the Portland cement and of the silica fume. Thus, at 50 °C AFm phases and ettringite are destabilised within a few weeks, while gypsum is formed due to the low hydroxide concentrations in the pore solutions. This destabilisation of ettringite and AFm phases is in contrast to unblended Portland cements, where monosulfate and either ettringite or monocarbonate are stable at 50 °C.

Online publication: 2014
Publication Type: abstract_only
Public price (Euros): 0.00