Effect of various anti-washout admixtures on the properties of non-dispersible underwater concrete

The present study investigates the effectiveness of using various viscosity modifiers admixtures (VMAs) as anti-washout admixtures (AWAs) to fabricate non-dispersible underwater concrete (UWC). Three types of AWAs categorized as natural, semi-synthetic, and synthetic polymers were used on this study; which include gum Arabic (GA), Xanthan gum (XG), super absorbent polymer (SAP), modified starch (MS), and Veegum (VG). The performance of UWC mixes was assessed in terms of rheological behaviour, mechanical performance, anti washout resistance, and physical phenomena such as bleeding and drying shrinkage The results indicate that among all AWAs, the GA, SAP, and XG are most suitable AWAs for fabricating UWC. Besides, improved compressive strength, higher anti washout resistance and lower shrinkage, these AWAs also increased plastic viscosity and thixotropic properties of UWC. The XRD, SEM, EDX, and FTIR analyses confirmed the greater formation of hydration products in UWC mixes fabricated using GA, SAP, and XG. (C) 2020 Elsevier Ltd. All rights reserved.