A new class of organosilane-modified polycarboxylate superplasticizers with low sulfate sensitivity

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作   者：

Wei Fan;  Francois Stoffelbach;  Jutta Rieger; 

作者机构：

94200 Ivry sur Seine;  UPMCSorbonne Universites and CNRS;  UMR 7615;  ESPCI - ParisTech;  10 rue Vauquelin 75231 Paris cedex 05;  3 rue Galilee;  France;  Laboratoire de Chimie des Polymeres (LCP);  UPMC Sorbonne Universites and CNRS;  Laboratoire de Physico-Chimie des Polymeres et des Milieux disperses (PPMD);  UMR 7610; 

关键词：

Polymers (D);  Dispersion (A);  Adsorption (C);  Sulfate (D);  Workability (A); 

期刊名称：

Cement and Concrete Research

i s s n：

0008-8846

年卷期：

2012 年 42 卷 1 期

页   码：

166-172

页   码：

摘   要：

It is well-established that a competitive adsorption exists between polycarboxylate superplasticizers (SP) and sulfate ions solubilized in the interstitial solution of cement paste, which may cause a loss of the dispersing properties. This has been explained by competitive weak ionic interactions between functional carboxyl groups and sulfate ions with cement grains. In this study, SPs including trialkoxysilane functional groups have been synthesized. Adsorption and dispersing properties of these SPs were evaluated in the presence of different concentrations of Na_2SO_4 added in aqueous solution. It appeared that a partial substitution of carboxyl groups by trialkoxysilane in the polymer makes them more resistant to sulfate ions. We suggested that the high adsorption capacity of these SPs results from the formation of strong bonds between hydroxysilane groups and calcium silicate hydrate phases. The improved compatibility of these new silylated SPs has been demonstrated through the formulation of two different concrete equivalent mortars.