Fresh Properties and Early Strength of Diatomaceous Earth Based Geopolymer Pastes

The fresh properties of concrete are crucial for ensuring it is easy to produce and process while achieving optimal performance during and after hardening. This research investigates the fresh properties of geopolymer paste made from diatomaceous earth with molarities of 10M and 12M. The liquid-to-solid ratio of the paste is 0.6, using NaOH and Na2SiO3 alkali activators in a 1:1 ratio. The fresh properties tested include normal consistency, flow, density, setting time, and 3-day compressive strength. The normal consistency and flow tests show that the 10 M diatomaceous paste, with 25% water from the binder, achieves a flow diameter of 12 cm. Meanwhile, the 12 M paste, with 24% water, has a smaller flow diameter of 11.8 cm. Setting time data indicate that the 12 M paste hardens faster than the 10 M paste, reaching a higher level of hardness at 45 minutes. The 3-day compressive strength test reveals that the 10 M paste has a strength of 19.91 MPa, while the 12 M paste is slightly stronger at 20.02 MPa. The density of the 10 M paste is 1.235 g/cm3, while the 12 M paste has a higher density of 1.292 g/cm3. Overall, this research demonstrates that the molarity of the alkali solution significantly influences both the fresh and mechanical properties of the geopolymer paste, with the 12 M paste showing faster setting time, higher density, and greater compressive strength than the 10 M paste.