Enhancing the performance of alkali-activated slag using plant-derived xylitol as a multi-functional additive

The use of xylitol – a plant-derived substance – as a multi-functional performance-enhancing additive for alkali-activated slag (AAS) was investigated. A comprehensive study was carried out to reveal the mechanisms of xylitol in affecting the performance of AAS mixtures in terms of fresh properties, hydration kinetics, compressive strength, autogenous shrinkage and so on. The experimental results showed that the addition of xylitol strongly retarded the setting process of AAS, with the AAS maintaining a high fluidity even with a low dosage of xylitol. However, the compressive strengths of AAS mortars with xylitol were enhanced owing to reduced porosity. For instance, with the addition of 0.2% xylitol, the 3-day and 28-day compressive strengths of AAS mortar were increased by 39.8% and 39.7%, respectively. Furthermore, the autogenous shrinkage of AAS mortars was reduced by 61.5% with 0.2% xylitol. Xylitol was found to be an effective retarder, plasticiser, compressive strength enhancer and autogenous shrinkage reducer for AAS.