Arrowroot as bio-admixture for performance enhancement of concrete

With the aim to promote sustainability by resorting to natural renewable resources, the potential of arrowroot (starch) as an admixture in cement concrete system was evaluated in this study. Arrowroot has a polymer structure as most of the chemical admixtures and it showed considerable effects on the setting time of cement, workability and durability of concrete. Unlike chemical admixtures, it has no consequent degrading effect on the environment. In this study arrowroot was added by 0.5%, 1%, 1.5% and 2.5% to cement weight. The addition showed delayed setting time of paste and increased workability of fresh mix for concrete. A better workability led to a better mixing of the constituents that resulted in better durability. Durability parameters were enhanced for concrete with arrowroot admixtures as confirmed by sorptivity, rapid chloride permeability test (RCPT) and rapid migration test (RMT) at 120 days of curing. A closer look to the microstructure of mortar via scanning electron microscopy (SEM) imaging of specimen without and with admixture revealed the effects of arrowroot in terms of pore structure and proportion of hydration products present. However, these effects are dose dependent. This study recommends arrowroot as a set retarding and workability enhancing bio-admixture and the optimum dose is suggested to be within 1%-1.5% of cement content.