Hybrid Lime-Pozzolan Geopolymer Systems: Microstructural, Mechanical and Durability Studies

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Construction

Background:

• Hydrated lime-pozzolan mixtures are common construction materials.
• Utilizing waste materials like rice husk ash (RHA) and spent fluid catalytic cracking (FCC) as pozzolans is crucial for sustainability.
• Geopolymer technology offers potential for enhancing material properties.

Purpose of the Study:

• To investigate the use of geopolymer materials to enhance the mechanical and durability properties of lime-pozzolan mixtures, creating "hybrid systems".
• To evaluate the performance of hybrid systems incorporating RHA and FCC as pozzolans.
• To explore the use of alternative silica sources (RHA, residual diatomaceous earth - RDE) for geopolymer activation to reduce carbon footprint.

Main Methods:

• Preparation of hybrid systems by replacing 30% of lime-pozzolan mixture with geopolymer.
• Activation of geopolymer with commercial reagents (NaOH, Na2SiO3) and alternative silica sources (RHA, RDE).
• Characterization using mechanical strength tests, thermogravimetric analysis (TGA), and durability studies (freeze-thaw, capillarity water absorption).

Main Results:

• Hybrid systems exhibited superior mechanical strengths at short and medium curing ages compared to traditional lime-pozzolan mixtures.
• Thermogravimetric analyses provided insights into the product formation within the hybrid systems.
• Hybrid systems demonstrated improved performance in freeze-thaw resistance and reduced capillarity water absorption.

Conclusions:

• Geopolymer-enhanced hybrid systems offer significant improvements in mechanical properties and durability over conventional lime-pozzolan materials.
• The use of waste materials (RHA, FCC) and alternative silica sources (RHA, RDE) in hybrid systems contributes to more sustainable construction practices.
• These findings support the viability of hybrid systems for applications requiring enhanced performance and reduced environmental impact.