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Highlights
•Strongly anionic PCE superplasticizers show a pH dependent dispersing effect.
•Strongly anionic PCEs perform better when pH value set to 1.5 than 7.
•Ettringite crystallization is influenced by PCE superplasticizers (pH 1.5 > pH 7).
•PCEs at pH 1.5 act as stronger ettringite morphology modifying agents than at pH 7.
Abstract
The impact of different pH values (1.5, 7) of polycarboxylate comb polymers (PCEs) on their dispersing performance was investigated via “mini slump” tests using different types of PCEs and cement compositions.
It was found that acidic strongly anionic PCE polymers performed better than their neutralized counterparts while PCEs with a weak anionic charge performed equally. In presence of strongly anionic neutralized PCEs more nano-ettringite was formed in cement paste than with the acidic counterpart, leading to a greater required dosage for an equal dispersing performance. Weakly anionic PCEs showed a much smaller difference, resulting in no pH dependent dispersing effectiveness.
（Quoted from Construction and Building Materials Volume 246, 20 June 2020, 118440）
https://www.sciencedirect.com/science/article/abs/pii/S0950061820304451
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