Synthesis and Performance Study of Clay‐Resistant Polycarboxylate Superplasticizer

ABSTRACT The accelerating global urbanization has led to a growing scarcity of natural sand and gravel resources, making the large‐scale application of alternative materials such as manufactured sand and recycled aggregates in concrete an industry consensus. However, these materials often contain certain amounts of clay minerals, which strongly adsorb polycarboxylate superplasticizers (PCEs) and severely impair their dispersing performance. This technical challenge remains inadequately resolved. To address this issue, this study breaks with the conventional approach of using a single polyether macromonomer for PCE synthesis. An innovative combined system of methylallyl polyoxyethylene ether (HPEG) and isopentenyl polyoxyethylene ether (TPEG) is employed as macromonomers to synthesize a conventional PCE (PCE‐HT) via aqueous free radical polymerization. On this basis, 2‐hydroxyethyl methacrylate phosphate (HEMAP) is introduced as a clay‐resistant functional monomer to prepare a clay‐resistant PCE (PCE‐KN). The performance differences between PCE‐HT and PCE‐KN are compared through tests including cement paste fluidity, zeta potential, adsorption amount, montmorillonite (MMT) interlayer spacing, concrete workability, and mechanical properties, supplemented by microscopic morphological characterization of hydration products. The results demonstrate that incorporating phosphate ester groups through molecular design significantly enhances the performance of PCE in high‐clay systems and effectively mitigates the performance degradation caused by clay adsorption.