Effect of Expanplast SP100 on the Workability of Concrete at Low Water Cement Ratio

Abstract

Workability is one of the most critical properties of fresh concrete, particularly when low water–cement ratios are adopted to achieve high strength and durability. However, reducing the water content often results in poor flowability, segregation issues, and difficulties in placement and compaction. This study investigates the effect of a polycarboxylate ether (PCE) based water-reducing admixture, Expanplast SP100, on the workability of concrete at a low water–cement ratio. Concrete mixes were prepared at a constant water–cement ratio of 0.41, with varying dosages of Expanplast SP100 ranging from 0.5% to 3% by weight of cement. Slump test results were used to evaluate workability performance and retention. The results demonstrate a significant improvement in workability with increasing admixture dosage, without the addition of extra mixing water. Optimal workability was achieved at dosages between 2% and 2.5%, beyond which only marginal improvements were observed. The findings confirm that Expanplast SP100 is highly effective in enhancing workability at low water–cement ratios, making it suitable for high-performance and pumpable concrete applications.