Abstract
This paper investigates the effect of the solids-to-liquids (S/L) and Na2SiO3/NaOH ratios on the production of palm oil boiler ash (POBA) based geopolymer. Sodium silicate and sodium hydroxide (NaOH) solution were used as alkaline activator with a NaOH concentration of 14 M. The geopolymer samples were prepared with different S/L ratios (0.5, 1.0, 1.25, 1.5, and 1.75) and Na2SiO3/NaOH ratios (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0). The main evaluation techniques in this study were compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed that the maximum compressive strength (11.9 MPa) was obtained at a S/L ratio and Na2SiO3/NaOH ratio of 1.5 and 2.5 at seven days of testing.
Highlights
The study of alkali-activated binder was started by Purdon in the 1940s in which blast furnace slag was activated with sodium hydroxide (NaOH) solution [1]
Palm oil fuel ash (POFA) is used as a cement replacement in concrete as palm oil boiler ash (POBA) contains coarse particles. As such this study investigates the utilization of POBA in geopolymers and the effect of solids-to-liquids ratio (S/L), alkaline activator ratio (Na2SiO3/NaOH) and curing temperature on geopolymer paste
At S/L ratio 1.0, 1.25 and 1.5 the maximum compressive strength was obtained at a Na2SiO3/NaOH ratio of 2.5
Summary
The study of alkali-activated binder was started by Purdon in the 1940s in which blast furnace slag was activated with sodium hydroxide (NaOH) solution [1]. The influence of the Na2SiO3/NaOH ratio (0.4, 1.5, 5.0, 10.0, and 15.0) in natural zeolite based geopolymers showed that increasing the Na2SiO3/NaOH ratio up to 1.5 increased the compressive strength, but beyond that the strength was decreased [12] This may be due to excessive sodium silicate that retarded the geopolymerisation process by the precipitation of Al-Si phase, which prevented contact between the reacting material and activating solution and decreased the activator content [13]. Palm oil fuel ash (POFA) is used as a cement replacement in concrete as POBA contains coarse particles As such this study investigates the utilization of POBA in geopolymers and the effect of solids-to-liquids ratio (S/L), alkaline activator ratio (Na2SiO3/NaOH) and curing temperature on geopolymer paste. The results of the geopolymer paste are evaluated in terms of compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM)
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