Title: Adsorption and Dispersing Properties of Lignosulfonates in Model Suspension and Cement Paste
Author(s): J. Gustafsson and K. Reknes
Publication: Symposium Paper
Appears on pages(s): 195-210
Keywords: adsorption; cement; polymer
Two softwood lignosulfonates of different molecular weights have been investigated for their adsorption behavior in cement pastes and in an alkaline model suspension. For the model suspension we also report the effect of the lignosulfonates on zeta-potential and suspension stability. In most investigations the results of the lignosulfonates are compared to that of a sulfonated naphtalene polymer. The adsorption of lignosulpfonates in cement pastes is found to depend strongly on molecular weight, and it is argued that this suggest a physical adsorption governed by the solvency of the lignosulfonates. With the model suspension, Mg(OH)2 particles in alkaline solution, an adsorption behavior similar to that in cement pastes is found, and the two lignosulfonates are shown to be equally effective dispersants of the Mg(OH)2 particles when no extra electrolyte is present in solution. However, when suspensions are made in aqueous solutions of high ionic strengths the high molecular weight lignosulfonate show the better dispersing properties.