Study on the foaming behaviour of allyl ether-based polycarboxylate superplasticizers

In this study, the foaming behaviour of allyl ether-based polycarboxylate (PCE) superplasticizers and the mechanism underlying this effect is presented. It was found that both purified allyl ether-co-maleic acid PCE and individual allyl ether macromonomer possess moderate surfactant properties but do not cause the excessive foaming known from industrially manufactured PCEs. Whereas, a mixture of purified PCE polymer and only small amounts (≥ 10%) of allyl ether macromonomer shows very strong foaming. This combination exhibits similar foaming action like industrially manufactured PCE superplasticizers. Apparently, the allyl ether macromonomer acts as a co-surfactant (foam stabilizer) to PCE which already presents a macro tenside. Minimizing the amount of unreacted allylether monomer in commercial PCEs provides a solution to obtain a less foaming product.