Adsorption of superplasticizer admixtures on alkali-activated slag pastes

被引:162
作者
Palacios, M. [1 ]
Houst, Y. F. [2 ]
Bowen, P. [2 ]
Puertas, F. [1 ]
机构
[1] CSIC, Eduardo Torroja Inst Construct Sci, Madrid 28080, Spain
[2] Ecole Polytech Fed Lausanne, Lab Technol Poudres, CH-1015 Lausanne, Switzerland
关键词
Alkali-activated slag cement; Admixtures; Portland cement; Adsorption; Rheology; SHRINKAGE-REDUCING ADMIXTURES; CEMENT MORTARS; HYDRATION; RESISTANCE; CONCRETE; STRENGTH; BEHAVIOR; SULFATE; ATTACK;
D O I
10.1016/j.cemconres.2009.05.005
中图分类号
TU [建筑科学];
学科分类号
0813 ;
摘要
Alkali-activated slag (AAS) binders are obtained by a manufacturing process less energy-intensive than ordinary Portland cement (OPC) and involves lower greenhouse gasses emission. These alkaline cements allow the production of high mechanical strength and durable concretes. In the present work, the adsorption of different superplasticizer admixtures (naphthalene-based,melamine-based and a vinyl copolymer) on the slag particles in AAS pastes using alkaline solutions with different pH values have been studied in detail. The effect of the superplasticizers on the yield stress and plastic viscosity of the AAS and OPC pastes have been also evaluated. The results obtained allowed us to conclude that the adsorption of the superplasticizers on AAS pastes is independent of the pH of the alkaline solutions used and lower than on OPC pastes. However, the effect of the admixtures on the theological parameters depends directly on the type and dosage of the superplasticizer as well as of the binder used and, in the case of the AAS, on the pH of the alkaline activator solution. In 11.7-pH NaOH-AAS pastes the dosages of the superplasticizers required to attain similar reduction in the yield stress are ten-fold lower than for Portland cement. In this case the superplasticizers studied show a fluidizing effect considerably higher in 11.7-pH NaOH-AAS pastes than in OPC pastes. In 13.6-pH NaOH-AAS pastes, the only admixture observed to affect the rheological parameters is the naphthalene-based admixture due to its higher chemical stability in such extremely alkaline media. (C) 2009 Elsevier Ltd. All rights reserved.
引用
收藏
页码:670 / 677
页数:8
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