It is well-established that a competitive adsorption exists between polycarboxylate superplasticizers (SP) with soluble sulfate ions solubilized in interstitial solution of cement paste, which may causes a loss of dispersing properties depending on the cement composition. Early reports suggested that this incompatibility is due to competitive weak ionic interaction between functional acrylate groups and solubilized sulfate ions with cement grains. In this study, SPs including trialkoxysilane functional groups have been synthesized via radical copolymerization of methacrylic acid, poly(ethylene glycol) methyl ether methacrylate and trimethoxysilyl propyl methacrylate. Adsorption and dispersing properties of these new SPs were evaluated in cement paste at different concentration of Na 2 SO 4 added in aqueous solution. Partial substitution of acrylate groups by trialkoxysilane in the polymer composition significantly enhances the compatibility with 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 present at the surface of C 3 S. The improved compatibility of these new silylated SPs with cements more or less rich in sulfate alkaline has been demonstrated through the formulation of two different concrete equivalent mortars.

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The present study is devoted to the enhanced detection of grinding aids (e.g. triethanolamine) in Portland cement, especially in its four major constitutive pure mineral phases. The method utilized was laser desorption Fourier transform mass spectrometry without any preconcentration step. It is shown that triethanolamine can be accurately detected at a dosage as low as ca. 150 ppm. © 1997 by John Wiley & Sons, Ltd. Received 9 June 1997; Accepted 11 August 1997 Rapid. Commun. Mass Spectrom. 11, 1612-1615 (1997 , called tricalcium aluminate, constituting 5 to 10% of clinker and denoted as C 3 A, and the ferrite phase which is tetracalcium aluminoferrite (Ca 2 AlFeO 5 ), constituting 5 to 15% of clinker and denoted as C 4 AF. In many cases, formulations based on a dilute aqueous solution of triethanolamine (TEA) are added to the clinker to improve the grinding operations during cement fabrication, by decreasing the energy required to achieve a given fineness of cement. The applicability of specific organic compounds as grinding aids in clinker has been recognized for a long time. It is supposed that their positive effect stems from the fact that they interact with the surface of the anhydrousphase particles to form a film which prevents agglomeration.

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