Analysis of Compressive Strength of Anhydrite Binder Using Full Factorial Design

Dalia Nizevičienė; Nora Kybartienė; Vacius Jusas

doi:10.3390/ma16186265

Analysis of Compressive Strength of Anhydrite Binder Using Full Factorial Design

Materials (Basel). 2023 Sep 18;16(18):6265. doi: 10.3390/ma16186265.

Authors

Dalia Nizevičienė¹, Nora Kybartienė², Vacius Jusas³

Affiliations

¹ Faculty of Electrical and Electronics Engineering, Kaunas University of Technology, Studentų Str. 48, LT-50254 Kaunas, Lithuania.
² Faculty of Chemical Technology, Kaunas University of Technology, Radvilėnų Str. 19, LT-50254 Kaunas, Lithuania.
³ Faculty of Informatics, Kaunas University of Technology, Studentų Str. 50, LT-50254 Kaunas, Lithuania.

Abstract

Flue gas desulfurization gypsum (FGD gypsum) is obtained from the desulphurization of combustion gases in fossil fuel power plants. FGD gypsum can be used to produce anhydrite binder. This research is devoted to the investigation of the influence of the calcination temperature of FGD gypsum, the activators K₂SO₄ and Na₂SO₄, and their amount on the compressive strength of anhydrite binder during hydration. The obtained results showed that as the calcination temperature increased, the compressive strength of anhydrite binder decreased at its early age (up to 3 days) and increased after 28 days. The compressive strength of the anhydrite binder produced at 800 °C and 500 °C differed more than five times after 28 days. The activators K₂SO₄ and Na₂SO₄ had a large effect on the hydration of anhydrite binder at its early age (up to 3 days) in comparison with the anhydrite binder without activators. The presence of the activators of either K₂SO₄ or K₂SO₄ almost had no influence on the compressive strength after 28 days. To determine which factor, the calcination temperature of FGD gypsum (500-800 °C), the hydration time (3-28 days) or the amount (0-2%) of the activators K₂SO₄ and Na₂SO₄, has the greatest influence on the compressive strength, a 2³ full factorial design was applied. Multiple linear regression was used to develop a mathematical model and predict the compressive strength of the anhydrite binder. The statistical analysis showed that the hydration time had the strongest impact on the compressive strength of the anhydrite binder using activators K₂SO₄ and Na₂SO₄. The activator K₂SO₄ had a greater influence on the compressive strength than the activator Na₂SO₄. The obtained mathematical model can be used to forecast the compressive strength of the anhydrite binder produced from FGD gypsum if the considered factors are within the same limiting values as in the suggested model since the coefficient of determination (R2) was close to 1, and the mean absolute percentage error (MAPE) was less than 10%.

Keywords: FGD gypsum; activators; anhydrite binder; calcination temperature; compressive strength; full factorial design.

Grants and funding

This research received no external funding.