期刊
CONSTRUCTION AND BUILDING MATERIALS
卷 24, 期 5, 页码 791-802出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.conbuildmat.2009.10.028
关键词
Metakaolin sand; Cement paste; Blend; Rheology; Hydration; Strength; Pore structure
资金
- Slovak and Spanish Grant Agencies [2007SK0005]
- Slovak Grant Agency VEGA [2/0053/09]
- Spanish Ministry of Science and Technology (MCyT) [BIA 2007-61380]
In the present work, the use of three Slovak poor metakaolin sands with different metakaolin content (36.0% (MK-1), 31.5 (MK-2) and 40.0% (MK-3)) and specific surface has been deeply studied as mineral addition for Portland cement. The percentage of metakaolin sands in the blended cements was 10%, 20% and 40%. The pozzolanic tests confirm that the three metakaolin sands show a high pozzolanic activity, comparable to a commercial metakaolin and silica fume. With respect to the theological behaviour, metakaolin sand-blended-cement pastes fit to Herchel-Bulkley model and their yield stress increases as the metakaolin content increases. MK-3 sand with the highest pozzolanic activity and highest specific surface induces the highest increase of the yield stress. From the calorimetric results it is concluded that the addition of MK-1 and MK-2 sands to Portland cement induces a delay up to 2 h of the precipitation of the main hydration products in the blended-cement pastes and decreases the maximum heat evolution rate. On the contrary, the incorporation of 40% of MK-3 sand shortens 6 h its apparition and increases significantly the maximum heat evolution rate. Additionally, the presence of the metakaolin sands reduces the heat released during the hydration process with respect to non-blended-cement pastes. The incorporation of metakaolin sand induces a decrease of the mechanical strength, being the decrease higher as the metakaolin sand content increases although they also produce a refinement in the pore structure and a decrease of the permeability. (C) 2009 Elsevier Ltd. All rights reserved.
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