Influence of high-charge and low-charge PCE-based superplasticizers on Portland cement pastes containing particle-size designed recycled mineral admixtures.

Abstract

Design: and use of engineered recycled mineral ad mixtures obtained from industrial and mineral waste are promising strategies to increase the range of materials suit able for use in cement - based composites. In this work, Portland cement - blended pastes con taining mineral ad mixtures designed for improving particle packing were evaluated in the presence of low - and high - charge poly car boxy late - based super plasticizers. The powders were obtained from basic oxy gen furnace slag, iron ore tailings, quartz mining tailings, and quartzite mining tailings. The zeta - potentials of the particles were obtained via electrophoretic mobility. The flow properties were evaluated by rheological tests per formed in a Couette type rheometer. The hydration kinetics was evaluated by isothermal calorimetry and an adapted method based on the Vicat needle test. The high - charge PCE and the finer mineral ad mixtures produced more stable blends. Coarser mineral ad mixtures led to increased flowability and delayed hydration compared to finer ones. Steel slag powders presented the most significant plasticizer effects, but also the largest set ting de lays and segregation tendency. Quartz – rich superfines reduced the set ting de lays caused by the super plasticizers. In summary, both super plasticizers were effective in improving flow prop er ties, but the high - charge PCE was effective in pre venting segregation in pastes con training mineral ad mixtures coarser and heavier than cement.