Influence of Different Sulfonated Naphthalene Polymers on the Fluidity of Cement Paste


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Title: Influence of Different Sulfonated Naphthalene Polymers on the Fluidity of Cement Paste

Author(s): F. Basile, S. Biagini, G. Ferrari, and M. Collepardi

Publication: Special Publication

Volume: 119


Appears on pages(s): 209-220

Keywords: cement pastes; chromatography; filtration; formaldehyde; naphthalene; plasticizers; sulfonate; viscosity; workability; Materials Research

Date: 9/1/1989

Eight samples of sodium salts of naphthalenesulfonic acid-formaldehyde condensates with different molecular weight have been synthesized by stopping the polymerization process at different reaction times between zero (monomer) and 14 hr at 112 C using a molar H2SO4/naphthalene ratio of 1.07 and a molar HCHO/naphthalene ratio of 1.20. The longer the reaction time, the higher the molecular weight. The condensates have been analyzed by Gel Permeation Chromatography to determine the chemical composition and average molecular weight. The condensates have been used as superplasticizers (0.4 percent of dry product by weight of cement) for cement paste (water/cement ratio = 0.35) and the fluidifying effect has been determined by the mini slump test. It was found that the fluidifying effect increased by reducing the content of monomer and increasing the molecular weight of the condensate. To confirm that the fluidifying effect of the condensate substantially depends only on the content of the higher molecular weight fraction, two samples of the condensate, with different reaction times and then with a different condensation degree have been subjected to an ultrafiltration process. This technique allows removal of the monomer and the lower molecular weight fraction. The two samples of the condensate, which had different fluidifying effects before the ultrafiltration process, behaved similarly as superplasticizers after the ultrafiltration process.