Title: Influence of Polymerization of Sulfonated Naphthalene Condensate and its Interaction with Cement
Author(s): M. Collepardi, M. Corradi,
and M. Valente
Publication: Symposium Paper
Appears on pages(s): 485-498
Keywords: adsorption; cement astes; cements; chemical analysis;
compressive strength; mortars material); naphthalene compounds;
physical properties; plasticizers; polymerization; viscosity;
water-cemen t ratio; workability; zeta potential.
More than twenty naphthalene sulphonated formaldehyde condensates have been synthesized with various degrees of polymerization. This was evaluated by viscosity measurements of the polymer in water solution. Polymer adsorption, zeta potential, fluidity and compressive strength of cement mixtures have been examined as a function of the degree of polymerization and the polymer dosage. Polymer adsorption, zeta potential and fluidity increase by increasing the polymer dosage in the range of 0.25 -2.00 % by weight of cement. Polymer adsorption, zeta potential, fluidity increase by increasing the degree of polymerization. However, above a certain degree of polymerization all the above mentioned properties do not change further. Cement particles adsorb the polymer molecules and this causes an increase in the electrical charge on the cement surface. This results in a better dispersion of cement particles and a more fluid system. However, even if there is a certain interaction between fluidity and zeta potential, the latter is not the only parameter controlling the fluidity of the system. At the same water/cement ratio, by increasing the degree of polymerization the strength is, in general, slightly increased and this seems to be related to a better dispersion of cement particles.