Abstract: There are several additives or admixtures used to change the composition of concrete or to accelerate or retard its hardening, curing, workability etc. Admixtures of bio origin have been used as reinforcement since ancient times. This study aims to use extract of Water Hyacinth, as bio-admixtures in cement and concrete. Consistency and setting time of cement is noted for 0, 10, 15 and 20% replacement of water with hydro extract of water hyacinth and the mechanical properties of concrete have been carried out. Workability increased with increase in replacement percentage (0-20%).Work is repeated with bio fine powder. The results showed a progressive increase in compressive strength with increase in percentage of replacement with bio admixture but delayed the setting time. The phyto-chemical analysis using GCMS revealed concentration of ligno cellulose, saturated and unsaturated fatty acids which make this admixture as a retardant. The present study has paved way for identifying water plant’s feasibility in structural strengthening of concrete.