Fluidity of Blended Cement with Polycarboxylate Based Superplasticizers Having Different Molecular Structure

【Author】

Daiki Atarashi;Tomofumi Sasabe;Shinji Tamaki;Masahiro Miyauchi;Etsuo Sakai;

【Abstract】

<正>Reducing emission of CO_2 is the most important mission in cement industry.And cement industry must contribute to recycling by utilization of industrial waste and by-products as raw materials or fuel.Recently,blended cement has been noted for environmental loading reduction.This paper discusses the adsorption and the dispersion mechanism of polycarboxylate based superplastisizer having different molecular structure in the blended cement system.Using a control stress type rheometer(rotational cylinder viscometer),the viscosity of the suspension was measured to estimate the apparent viscosity at a shear stress of 200 Pa.The absorbed amount of polymer calculated from the concentrations of the polymer in the initial solution and the liquid phase.The unabsorbed polymer concentration was measured by carbon analysis using a total organic carbon analyzer(TOC).Polycarboxylate based superplasticizer having smaller amount of functional groups is adsorbed on blast furnace slag(BFS) compared with ordinary Portland cement(OPC).And polycarboxylate based superplasticizer having larger amount of functional groups is adsorbed on both BFS and OPC.In the case of polycarboxylate based superplasticizer having larger amount of functional groups,the fluidity of cement paste was influenced by the replacement ratio of BFS.On the other hand,in the case of polycarboxylate based superplasticizer having smaller amount of functional groups,the fluidity of cement paste was not influenced by the replacement of BFS.Therefore polycarboxylate based superplasticizer having smaller amount of functional groups could be suitable for blended cement. Originality The adsorption and dispersion mechanisms of polycarboxylate based superplasticizers having different molecular structure were cleared in this study.We clarified the adsorption behavior of polycarboxylate based superplasticizer on OPC and admixture depends on the molecular structure of polycarboxylate based superplasticizer.And from the results,we can suggest the suitable molecular structure of polycarboxylate based superplasticizer for blended cement.Therefore,our research results can contribute to reducing emission of CO_2 in cement industry.

【Keywords】

Blast furnace cement;;Blast furnace slag;;Polycarboxylate based superplastisizer;;Fluidity;;Apparent viscosity;;Amount of adsorbed polymer

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