Synthesis and properties of a novel structure of phosphated superplasticizer

Abstract

In this work, a novel structure of phosphated superplasticizer (PNH) prepared by Mannich reaction of polyetheramine, phosphorous acid and formaldehyde was reported. Results of cement paste test indicated that PNH superplasticizer exhibits excellent fluidity retention and retarding properties. The PNH superplasticizer also showed better clay tolerance than polycarboxylate superplasticizer (PCE), as the slump flow decreased by 7.20% and 18.22% when 0.5% and 1.0% of montmorillonite were added respectively, while the slump flows of PCE superplasticizer decreased by 29.18% and 67.81% respectively. Adsorption isotherms and conductivity measurements indicated that phosphate group with two negative charges can coordinate with more Ca2+, which enables its complexation and adsorption capacity much stronger than carboxylic group. Setting time analysis and isothermal calorimetry measurements demonstrated that PNH superplasticizer using phosphate as adsorption group has an obvious retarding ability as it could delay hydration process and reduce hydration heat. Although the phosphated superplasticizers showed a lower dispersion ability, comparing with PCE superplasticizer, the special structure and properties provide the potential to explore new kind of superplasticizers in the future.