Use of Non-Purified Polycarboxylate Ether (PCE) as Superplasticizer - Structural Determination and PCE/Cement Interaction

Objective: Aim of this paper is to investigate the interactions between industrial-grade polycarboxylate ether (PCE) polymers and ordinary Portland cement to assess whether is possible to draw structure/performance relations for impure, yet fully characterized, polymers. Method: To this end thirteen PCE polymers were synthesised in industrial fashion, deeply analyzed and tested in cement paste. Chemical stability and adsorption behaviour have been evaluated through gel permeation chromatography technique, leading to insights regarding the plasticization timing and the adsorption control. Results: All the results were interpreted and critically discussed by invoking the characteristics of initial dispersers and workability retainers; furthermore a comprehensive description has been attempted through the Gay and Raphael conformation plot, based on the establishment of which molecular feature affects each step of the PCE's working mechanism. Conclusion: The results confirm many of the findings despite the imperfect nature of the chosen polymers and show that common impurities, such as unreacted side chains, do not noticeably interact with the binder. In particular it is clear that the limiting stage of the entire action lies on adsorption rate and occurrence, which seems to be ruled by the absolute value of charge per chain and by the conformation regime.