Influence of maltodextrin retarder on the hydration kinetics and mechanical properties of Portland cement

Abstract

In this study, the effect of maltodextrin on the hydration kinetics of ordinary Portland cement was investigated. Additionally, the impact of maltodextrin on the physical and mechanical properties of cement is further studied via setting time, fluidity and mechanical strength tests which has been conducted with different curing times (16 h, 1 d, 3 d, 28 d). The results revealed the impact on the mechanical properties of OPC is dosage and time dependent. At the early curing time of 16 h, the addition of maltodextrin decreased the compressive strength of all mortar samples substantially; a higher dosage of maltodextrin resulted in even lower compressive strength. However, at extended curing times such as 1 d, 3 d or 28 d, the impact on the compressive strength of OPC is dependent on dosage: relatively low dosages (0.01–0.05%) of maltodextrin increased the compressive strength of mortar, whereas higher dosages (≥0.1%) of maltodextrin was found to decrease the compressive strength of mortar. Furthermore, the time – dependent development of hydration products was monitored via in-situ XRD at the different ages of cement hydration. The results showed that the addition of maltodextrin delays cement hydration which results in less hydration products like Portlandite and ettringite. Finally, the mode of interaction between maltodextrin and cement was assessed through adsorption and zeta potential measurements. The adsorption as well as zeta potential measurements confirm that the retarding mechanism of maltodextrin relies on adsorption on the surface of cement particles.