Rheology of slag-based geopolymer concrete using corncob ash as a pozzolanic material

This study examined the rheology of slag-based geopolymer concrete (GPC) incorporated with corncob ash (CCA). In an attempt to sustain an effective way of recycling our waste products and remedying land, water and air pollution, the study harnessed both ground granulated blast furnace slag (GGBFS) and corncob ash (CCA) as sustainable binders. In addition, sodium hydroxide (NaOH) solution and sodium silicate gel (Na2SiO3) were used as alkaline liquid. Method of volume by batching was adopted where GGBFS was replaced by CCA in 0, 20, 40, 60, 80, and 100%. The paste normal consistency was used to prepare the specimens for both initial and final setting times of the fresh concrete. However, slump and compacting factor values on the freshly made concrete were determined on both grade 30 MPa and grade 40 MPa concretes using the activation of 12, 14 and 16 molar concentrations of NaOH pellets. The experimental results show that the initial and final setting times increased with increasing CCA content; while the slump, compacting factor tests also increased with increasing CCA content. On the other hand, the workability of GPC reduced with increasing grade of concrete and molarity of NaOH solution. The study finding is beneficial in that fresh concrete remains workable for longer periods, thus resulting in lesser joints. It is also advantageous especially in hot weather conditions