Design of a novel starch-modified MPEG PCE for enhanced slump retention in alkali-activated slag binder

Alkali-activated slag (AAS) is a promising low-carbon binder to partially or even fully replace cement clinker to beneficially reduce the CO 2 footprint of the construction sector. However, conventional MPEG PCE polymers (e.g. MAA-45PC6), have shown ineffective in dispersing AAS systems and maintaining slump retention. To overcome these challenges, a bio-inspired concept of incorporating starch into the MPEG-based PCE was proposed in this study and was found to be effective in both providing initial fluidity and extending the workability over time. Additionally, the starch-based MPEG polymer notably increases the solubility of MPEG-based polymers in NaOH-activated systems. The abundant hydroxyl functionalities of starch help delay the rapid setting of AAS binders. The underlying mechanisms were elucidated through comprehensive studies on physicochemical properties, adsorption isotherms and hydration evolution. This study aims to provide an eco-friendly insight into the use of both low-carbon binders and bio-based superplasticizers to facilitate the eco-balance of concrete.