The effect of superplasticizers' chemical structure on their efficiency in cement pastes

The impact of chemical structure of four new-generation superplasticizers-derivatives of either acrylic acid (denoted as SP-A and SP-B) or maleic acid (SP-C and SP-D) - on their efficiency in cementitious pastes was studied. Gel permeation chromatography (GPC) and Fourier-Transformed Infrared Spectroscopy (FTIR) were applied to investigate the superplasticizers' molecular structure. The performance of a superplasticizer, i.e. reduction in plastic viscosity, was proven to be dependent on its chemical structure. The maleic-based superplasticizers, having longer backbones and side chains as well as carboxylic groups (COO-), thus displaying higher molecular mass and hydrophilicity, are more efficient. On the other hand, the acrylic acid derivatives, with shorter backbones and side chains and without carboxylic groups, appear less efficient. It was also proven that the maleic-based superplasticizers slow the hydration process down to a much greater extent than acrylic acid-derived superplasticizers. (C) 2012 Elsevier Ltd. All rights reserved.