International Journal of Civil & Structural Engineering
Author(s) : ALI MARDANI-AGHABAGLOU, Muhammet GÃ¶khan Altun, SÃ¼leyman Ã–zen, SULTAN HUSEIN BAYQRA
In this study, the effect of anionic functional group change of polycarboxylate-ether based water reducing admixture on some fresh state properties and compressive strength of the cement paste and mortar mixtures was investigated. For this purpose, in addition to the control admixture having 100% of carboxylate as anionic functional group, four different types of admixture were synthesized by replacing 10 and 30 mol% of anionic functional group with sulfonate and phosphate functional groups. In all admixtures anionic/non-ionic group ratios, free non-ionic group contents, molecular weights, main chain and side chain lengths were kept constant. In all mixtures CEMI 42.5R type cement were used as binder. In mortar mixtures water/cement ratio, sand/binder ratio and slump-flow values were kept constant as 0.485, 2.75 and 270Ã‚Â±20 mm, respectively. According to the test results, flow time of the paste and mortar mixtures did not significantly change by substitution of carboxylate anion functional group with sulfonate one by 10 mol%. However, the flow performance of the mixtures was adversely affected upon the increase of mentioned substitution rate to 30%. The flow performances of the paste and mortar mixtures improved by replacing of carboxylate anion functional group with the phosphate one. The substitution of anionic monomer with sulfonate or phosphate functional groups had no significant effect on the mini-slump values of the paste mixtures. The substitution of the anionic monomer of the admixtures with sulfonate positively affected the time-dependent slump-flow performance of the mortar mixtures, while the substitution with phosphate monomer showed a negative effect.The presence of sulfonate and phosphate functional groups as anionic monomer of the water reducing admixtures did not cause a significant change in the early and ultimate strength and water absorption capacity of the mortar mixtures.