Effect of nano-silica on rheology and fresh properties of cement pastes and mortars

Amorphous nano-silica (nS) particles (0–2.5 wt%) by cement were incorporated in cement pastes and mortars, and their effect on the fresh state behaviour was analysed. Rheological tests showed that after 75 min from the mixing start, the mortar having 2.5 wt% nS shows insufficient flowability to allo...

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Bibliographic Details
Published inConstruction & building materials Vol. 23; no. 7; pp. 2487 - 2491
Main Authors Senff, Luciano, Labrincha, João A., Ferreira, Victor M., Hotza, Dachamir, Repette, Wellington L.
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 01.07.2009
Subjects
Fresh properties
Mortars
Nano-silica
Portland-cement pastes
Rheology
Mortars
Rheology
Nano-silica
Fresh properties
Portland-cement pastes
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Summary:Amorphous nano-silica (nS) particles (0–2.5 wt%) by cement were incorporated in cement pastes and mortars, and their effect on the fresh state behaviour was analysed. Rheological tests showed that after 75 min from the mixing start, the mortar having 2.5 wt% nS shows insufficient flowability to allow its continuous monitoring in a Viskomat PC viscometer. The influence of nS content was better observed on yield stress when compared with plastic viscosity values (the first increased about 66.5% while the latter just increased 3.6%). With nS addition, spread, setting time and the moment to reach the maximum temperature decreased 33%, 60% and 51.3%, respectively, when compared with samples without nS. X-ray diffraction showed presence of calcium hydroxide after 9 h in the sample with 2.5 wt% nS. The air content increased 79% and apparent density decreased 2.4% when nS was added.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2009.02.005