Production of Geopolymer Composite from Sugarcane Bagasse Fly Ash Using Potassium Hydroxide and Sodium Sulfate as Activators

Author : Ubiña, Lemuel Joshua Binayug
Major Adviser : Sanchez, Denise Ester S.
Committee Members : Gatdula, Kristel M.; Bautista, Ramer P.
Year : 2019
Month : June
Type : Thesis/Practicum/Innovationeering
Degree: BS
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Abstract

Sugarcane bagasse fly ash (SBFA), a waste product from sugar industries, was utilized to produce geopolymer composites with potassium hydroxide (KOH) and sodium sulfate (Na₂SO₄) as activators. SBFA has 45.92 % SiO₂ and 9.58 % Al2O₃ and was enough to be an alumino-silicate source for geopolymerization. Mixture design was generated to evaluate the effects of varying mass fractions of SBFA, KOH, and Na2SO4 on the compressive strength and microstructural characteristics. The geopolymer composites displayed very low compressive strength compared to ordinary Portland cement and has a percent difference of 96.17%. The possible reasons are high carbon content and high particle size diameter of the SBFA and, not enough thermal curing. The highest compressive strength was only 0.264 MPa with mass fractions of 0.757 SBFA, 0.243 KOH and no Na2SO4 at 12 M concentration of KOH. The effects of the mass proportions on the compressive strength of geopolymer composite were statistically significant (P value =0.0222) for the 12 M KOH concentration while they were insignificant (P value = 0.3956) for the 10 M KOH concentration. Through Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR), the highest compressive strength exhibited geopolymerization process. SEM images showed geopolymer clumps surrounding the SBFA and FT-IR spectra showed that Si-O-Si and Si-O-Al polymeric bonds were present at 1000 to 1100 cm-1 wavelength. The total cost of geopolymer composite upon utilizing 1 kg of SBFA was 12.61 PhP and was more expensive than OPC (9.16 PhP), therefore the produced geopolymer still cannot replace OPC.

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