Characteristics of fly ash based concrete prepared with bio admixtures as internal curing agents

Concrete is the most widely used material which is structural and versatile in nature owing to its heterogeneous and complex structures. Curing of concrete is an important stage to attain its intended strength and durability. The conventional method of water curing is not very effective and sometimes ignored due to water scarcity and labour problems. Internal curing of concrete by adding water soluble material can hold the mixing water against evaporation and further enhance the hydration of cement. The chemical admixture namely polyethylene glycol (PEG) is able to reduce water evaporation by a retaining function, lead to strong and durable concrete without water curing but it is expensive. This paper presents an attempt of using bio materials namely Spincea oleracea (S. oleracea) & Calatropis gigantea (S. oleracea) as internal curing agents in concrete. To confirm the presence of hydroxyl or ether group in S. oleracea and S. oleracea like PEG for water retention, UV-visible and FT-IR studies are carried out on these plant extracts. To evaluate their internal curing property, FT-IR, XRD and SEM analysis are carried out on M20 grade fly ash based concrete powder sample with internal curing agents and compared with the performance of conventionally water cured concrete powder samples. Compressive strength and bond strength of concrete with bio admixtures are compared with the internal curing property of PEG and also with conventionally water cured concrete. (C) 2020 Elsevier Ltd. All rights reserved.