Investigation of geopolymer concrete production by using calcium bentonite

In this study, fly ash based geopolymer concretes were created by using a mixture of arc furnace slag and basic basaltic pumice as aggregates, a fly ash (Class F) and alkaline activator for lightweight concrete production. Box Behnken test design (Design Expert11) was concluded to discover the active curing parameters. This study focused on the possibility of fly ash based geopolymer concrete to which calcium bentonite has been added. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution were used to produce the alkaline activator. The concentration of NaOH solution was fixed at 12 Molar, ratio of fly ash/alkaline activator and sodium silicate/NaOH fixed at 1.5 and 2.5, respectively. Calcium bentonite was added in range 5% - 15% from the mass of mixture and all the samples were cured at room conditions. The uniaxial compressive strength, Point load resistance, and pundit sonic speed were conducted on geopolymer concrete to assess the proportions that provide the best properties of the concrete. Uniaxial compressive strength, Point load resistance, and pundit sonic speed results have been attained. It is revealed that 5% replacement of calcium bentonite contributed to maximum uniaxial compressive strength, point load resistance, and pundit sonic speed of 50.03 MPa, 13,2 kN and 4 Km/sn at 28 days.