Influence of Sodium Gluconate Retarder on the Absorption Characteristics of Polynaphthalene Sulphonate Superplasticizer

摘要

By using two pastes of cement-water system and fly ash-water system, the influence of sodium gluconate (SG) on the absorption characteristics of polynaphthalene sulphonate superplasticizer (PNS) on the surface of powder particles was investigated. The results show that when PNS not reaching up to saturated dosage, the proper amount of SG can obviously reduce the fluidity loss of the above two pastes, but also reduce the absorption amount of PNS on the surface of particles, and the reducing extent of adsorption amount increases with time. The X-ray photoelectron spectroscopy (XPS) shows that for the cement paste with only PNS, the carbon atomic concentration on the surface of cement particles at the hydration time of 60min is distinctly lower than that at the hydration time of 5min; for the cement paste with SG and PNS, the carbon atomic concentration at 60min is nearly equal to that at 5min. The results indicate that the competing absorption and the influence on the transformation rate of PNS adsorpti ve styles on cement particle surface based the dynamic absorptive models are an important reason for SG reducing the fluidity loss of the cement paste with PNS and SG