Analysis of Compressive Strength of Anhydrite Binder Using Full Factorial Design

Area of Science:

• Materials Science
• Civil Engineering
• Chemical Engineering

Background:

• Flue gas desulfurization gypsum (FGD gypsum) is a byproduct of fossil fuel power plants.
• FGD gypsum can be repurposed into valuable anhydrite binders.
• Understanding factors influencing anhydrite binder properties is crucial for sustainable construction materials.

Purpose of the Study:

• To investigate the impact of calcination temperature, activators (K2SO4, Na2SO4), and their amounts on anhydrite binder compressive strength.
• To determine the primary factor influencing compressive strength through statistical analysis.
• To develop a predictive mathematical model for anhydrite binder strength.

Main Methods:

• Calcination of FGD gypsum at temperatures ranging from 500-800 °C.
• Addition of K2SO4 and Na2SO4 activators at varying percentages (0-2%).
• Hydration of anhydrite binder samples over 3-28 days.
• Compressive strength testing.
• Application of a 2^3 full factorial design and multiple linear regression for analysis.

Main Results:

• Increasing calcination temperature initially decreased early-age compressive strength but increased it significantly after 28 days.
• Activators K2SO4 and Na2SO4 substantially enhanced early-age strength but had minimal long-term impact.
• Hydration time was identified as the most significant factor affecting compressive strength, followed by K2SO4's influence over Na2SO4.
• A predictive model with R2 close to 1 and MAPE < 10% was developed.

Conclusions:

• Calcination temperature and hydration time are critical for optimizing FGD gypsum-based anhydrite binder strength.
• Activator choice (K2SO4 > Na2SO4) influences early performance, but long-term strength is primarily governed by hydration and calcination conditions.
• The developed mathematical model accurately predicts anhydrite binder compressive strength within the studied parameter ranges.